Roles of pre-treatment time and junctional proteins in Caco-2 cell microparticle uptake

Microparticle uptake in the small intestine is relevant to both the delivery of pharmaceutics and exposure to environmental pollutants. The Caco-2 enterocyte model is a useful tool to study the parameters that affect epithelial microparticle permeability and the mechanisms controlling them. The current study used this model to explore further the different effects of 10% ethanol v/v or ice on transepithelial resistance (TER), microparticle uptake and immunofluorescent labelling of intercellular junctions. The same exposure times for both treatments were used, rather than those shown in the literature to produce demonstrable changes induced by each. The effects of both pre-treatments were greater after 60 min than after 15 min. Ethanol pre-treatment for 60 min decreased TER, increased particle uptake and was associated with a disorganisation of tight and adhering junctional proteins. Pre-treatment with ice for 60 min however, increased TER, decreased particle uptake and was associated with concentration of intercellular junctional proteins in a more constrained manner. These findings on the effects of pre-treatment with ethanol or ice for 60 min suggest that the extent of uptake is influenced by changes in the distribution of intercellular junctional proteins.

Culture conditions and treatments affect Caco-2 characteristics and particle uptake

Small intestinal microparticle uptake via a paracellular route is relevant to oral drug delivery and environmental pollution. In vitro investigation uses latex microparticle passage across a confluent Caco-2 cell epithelium. This paper examines the influence of culture conditions on transepithelial resistance (TER); cell dimensions from confocal microscopy; and number of particles below the epithelium. Variables investigated include level of initial TER; multiple TER measurements; involvement of medium; cell source; and pretreatment with ethanol or a range of temperatures. Data were collected after exposure to 2 microm latex particles for 5-120 min: sham groups were exposed to pretreatment but not particles. The results highlight the importance of very precise control of the experimental environment; confirm the pattern of sequential-TER increase/decrease in groups exposed only to particles and show accompanying increases in cell dimensions. Greater particle uptake was associated with ethanol-induced decreased TER, decreased cell height and increased intercellular spaces, similar to previous findings for external irradiation. Low temperatures raised TER but, despite this, cooling did not alter particle uptake. In conclusion, culture microenvironment and sham treatment are crucial considerations in studies of epithelial microparticle uptake in vitro.

Uptake of inert microparticles in normal and immune deficient mice

Intestinal microparticle uptake is important for drug delivery, environmental pollution and multiple organ dysfunction syndrome. This paper explores further whether uptake occurs at mucosa associated lymphoid tissue (MALT) via the microfold (M) cells of Peyer's patch domes or through villous epithelium. It does this by comparing the results of exposure of either severe combined immunodeficient (SCID) mice (lacking MALT) or normal BALBc mice, to oral gavage with 2 microm fluorescent latex microparticles. At 5 and 30 min after gavage, full circumference samples along the small intestine were processed for fluorescence microscopy and microparticle numbers were collected for surface and tissue sites. Uptake occurred in both BALBc and SCID mice within 5 min of particle administration and increased further in the following 25 min. In BALBc mice, almost all particles (96%) are in non-MALT sites in MALT circumference samples, with very few at the domes: uptake was also substantial in entirely villous samples. In SCID mice, particle numbers were only slightly lower than those of the BALBc mice, and occurred exclusively by the villous route. These findings confirm that the villous uptake route must be considered when assessing the extent of the dose delivered following pharmaceutical or toxicological oral exposure to microparticles.

Parameters influencing intestinal epithelial permeability and microparticle uptake in vitro

The hypothesis that, in vivo in situ, villous uptake of 2 microm latex microparticles involves changes at enterocyte tight junctions (TJs) was tested using Caco-2 cells on porous membranes. Epithelial permeability was measured by transepithelial resistance (TER) and particle numbers in surface, intraepithelial and sub-epithelial compartments by microscopy. Apical particle or medium addition initially closed TJs, but this was subsequently reversed in particle-treated groups. Peristaltic onward movement of a bolus was simulated by removing apical particles after an exposure period and leaving the remaining particles to interact with the epithelium: this produced marked TJ loosening during the interaction period. For particle exposure groups, the early similarity with particle numbers in vivo taken up in young adult rats became less marked with time, although bolus removal counteracted this tendency. The TJ response to vasoactive intestinal polypeptide (VIP) was time-dependent. Adsorbed and intraepithelial particle numbers increased with particle exposure time; epithelial-associated microparticle aggregation varied with treatment and submembranous particles were seen in all groups. Correlation between TER changes and particle numbers suggests TJ loosening may be important in microparticle uptake. This Caco-2 model gives epithelial particle numbers that approximate well to published figures for microparticle uptake in vivo and allows effective microenvironmental manipulation.

Factors influencing intestinal microparticle uptake in vivo

The aim of this study is to compare microparticle uptake in animals of different ages, gender and species and at different time points. The 2mum latex/in vivo in situ model uses the observation of animal responses or post-mortem changes and also particle identification by fluorescence microscopy in nine sequential intestinal segments and secondary sites. The wide size range of animals studied requires particle numbers in tissue compartments to be related to intestinal tissue section area through a circumference measurement. Area under the curve (AUC) data for particles in intestinal tissue are plotted against measurements of intestinal length, allowing comparisons to be made across different ages and species and between males and females. The percentage uptake of administered dose and particle numbers in macerated tissue are also reported. Some parameters, in particular species, do not appear to affect the extent of microparticle uptake, which ranges from 0.12 to 0.32% of the administered dose. Particle uptake does, however, vary with age, being significantly greater in young adult males (7 weeks) than in younger (3 weeks) and older (17 and 52 weeks) age groups. It is concluded that age is more important in determining the extent of uptake than gender or species.

Effects of radiation damage on intestinal morphology

The current flow of papers on intestinal structure, radiation science, and intestinal radiation response is reflected in the contents of this review. Multiparameter findings and changes in compartments, cells, or subcellular structure all contribute to the overall profile of the response. The well-recognized changes in proliferation, vessels, and fibrogenesis are accompanied by alterations in other compartments, such as neuroendocrine or immune components of the intestinal wall. The responses at the molecular level, such as in levels of hormones, cytokines, or neurotransmitters, are of fundamental importance. The intestine responds to localized radiation, or to changes in other organs that influence its structure or function: some structural parameters respond differently to different radiation schedules. Apart from radiation conditions, factors affecting the outcome include the pathophysiology of the irradiated subject and accompanying treatment or intervention. More progress in understanding the overall responses is expected in the next few years.

Radiation effects in the small bowel of the diabetic mouse

PURPOSE

Irradiation of the small intestine in the mouse induces damaging structural alterations to the architecture of the enteric mucosa. There is growing interest in the possible relevance of underlying additional pathology when appreciating the total response of tissues to irradiation. The possibility that small intestinal mucosal abnormalities in the streptozotocin-induced diabetic mouse may exacerbate radiation-induced injury was tested by examining the combined effects of the two treatments.

MATERIALS AND METHODS

Streptozotocin-diabetic and -non-diabetic mice were exposed to 10 Gy abdominal X-radiation. Profiles of mucosal epithelial cell populations were quantified and comparisons with corresponding groups of unirradiated mice made on the third day post-irradiation.

RESULTS

The histological appearances of the small intestinal mucosa were similar in both groups of irradiated mice, but the numbers of profiles of crypts and of columnar, goblet, Paneth and entero-endocrine cells were depressed in these groups when compared with values in corresponding groups of unirradiated mice. However, the expression of radiation damage in the diabetic mouse was less severe than in the non-diabetic mouse, particularly in the jejunum where the changes attendant on the onset of diabetes were most marked.

CONCLUSION

These findings suggest that the response of mouse to radiation may be moderated by the presence of this type of pathophysiology. However, there is no evidence that the damage produced by streptozotocin-induced diabetes and radiation is additive.

Variations in cell and structure populations along the length of murine small intestine

Previous workers have reported a range of structural variations occurring along the length of small intestine. These studies have concentrated on the major intestinal components with little information available on the intersite variation of other members of a highly heterogeneous population. Using resin histology, the current study has collected data per circumference for all definable structural features within the murine intestinal wall, along with measurements for epithelial, muscle, nerve and connective tissue areas, and villous height and cryptal depth. Seven different sites along the length of the small intestine were examined. Following statistical comparisons a number of features exhibited no intersite variation; these were numbers of villi, submucosal vessels, myenteric nerve plexus profiles, inner muscle nuclei and apoptotic bodies as well as measurements for tissue areas and cryptal depth. Variations were seen between sites for crypts, enterocytes, villous and cryptal stromal cells, cryptal goblet cells, cryptal non-secretory epithelial cells, Paneth cells, endocrine cells, intra-epithelial lymphocytes, submucosal nerve plexus profiles, outer muscle nuclei and mitotic figures. A reduced villous height was observed caudally. Certain correlations between villous height/crypt number and constituent parameters have been noted. The results provide a complete description of how each definable structural feature within the gut wall varies at regular intervals along the length of the small intestine in C57 BL mice. A number of previously unreported variations have been described. The work provides a comprehensive data bank for future intestinal investigations.

Acute and protracted radiation effects on small intestinal morphological parameters

PURPOSE

To compare the responses of small intestinal morphological parameters after acute and protracted doses of radiation.

MATERIALS AND METHODS

Male C57BL6 mice were examined 6, 24 and 72 h after whole body gamma-irradiation, given either as an acute 5 Gy dose, or as a protracted (continuous) dose of 20 cGy per day for 25 days to a total dose of 5 Gy. Many different structural parameters at both the light microscopical and ultrastructural levels were assessed quantitatively.

RESULTS

At different time points following both schedules there were changes in the number of villous enterocytes, goblet cells, lamina propria cells and mitotic figures. Ultrastructural changes occurred in the epithelium. Many of the parameters that showed changes following the protracted schedule appeared to be returning to normal within 3 days of the cessation of radiation, a finding which was in contrast with the acute dose. The protracted schedule produced increases in the number of Paneth cells and in the length of enterocyte microvilli.

CONCLUSIONS

Many of the responses that occurred after the protracted schedule suggest that adaptive mechanisms may be being triggered following persistent exposure to radiation.

Cortical bone responses to 2G hypergravity in growing rats

BACKGROUND

Rat cortical bone adaptation to chronic hypergravity (2G) was studied using young growing male Wistar rats (60 d).

METHODS

Animals (10 rats) were subjected to chronic hypergravity (14 d) in order to understand the plastic nature of bone under a constant hypergravity stress using a special rodent habitat that was attached to a 12-ft. radius centrifuge. Also, an equal number of stationary controls were housed in a rodent vivarium containing identical cages that were used for centrifugation. After 14 d of centrifugation, femur bones were excised and prepared for morphological and biochemical measurements.

RESULTS

Results showed that 2G had significantly shortened the femurs (3%) and reduced the cortical bone area (13%). In particular, hypergravity induced significant reductions in the thicknesses of cortical bone at the anterior (13%) and medial regions (15%) of the mid-diaphysis. However, femoral bone density, collagen and calcium concentrations were unaltered. The content of mature, stable bone collagen cross-links hydroxylysylpyridinoline (HP), lysylpyridinoline (LP), were significantly greater in bones from centrifuged animals.

CONCLUSION

Our findings suggest that short term exposure to 2G does not enhance bone formation or induce changes in cortical bone composition, or alter specific gravity. These data also suggest that bone maturation as reflected by collagen cross-linking is upregulated. However, it is undetermined at this time whether the enhanced content of mature bone collagen in the centrifuged rats is a result of either an increased rate of cross-linking or reduction in the degradation of "older collagen."

Dietary fibre and intestinal microflora: effects on intestinal morphometry and crypt branching

BACKGROUND

Fermentable dietary fibre has many effects on the gastrointestinal tract. One is to alter epithelial crypt cell proliferation, especially in the colon. A discrepancy between epithelial cell production rates and intestinal weights has been noted previously: crypt cell production rates only increase if bacterial fermentation occurs, but intestinal wet weight can increase in the same animals without bacterial fermentation of fibre.

AIMS

To quantify intestinal cell populations in order to resolve the above paradox.

METHODS

Conventional and germ-free rats were fed fibre-free or fibre supplemented diets and their intestines were quantified by morphometry.

RESULTS

There was evidence of fibre associated muscle hypertrophy in the colon, but the main effect of fibre was an increase in the number of crypts per circumference and also the number of branched crypts in the proximal colon in both groups. There was also a large increase in the number of branched crypts in the mid colon of the germ-free rats (both fibre-free and fibre supplemented). Fibre had a direct (bacteria independent) effect on goblet cells in the small intestine and a direct effect on the goblet cells in the colon, which was attenuated by the presence of bacteria. There was a notable decline in the number of enteroendocrine cells in the small intestine of the germ-free animals.

CONCLUSIONS

Fibre has several direct and indirect effects on the gut. In the proximal colon it can directly increase the number of crypts present. This provides a means for increasing intestinal mass in addition to intestinal crypt cell production.

A morphological study of the enteric mucosal epithelium in the streptozotocin-diabetic mouse

In the acutely diabetic rat, the polyphagia-induced increase in the weight of the small intestine is associated with reported increases in mucosal mass. Whereas, some of the individual mucosal components in the rat have been studied, comparable information for the acutely streptozotocin-diabetic mouse is lacking. A detailed morphological comparison of the epithelium of the small intestinal mucosa in control and untreated streptozotocin-diabetic mice was therefore undertaken. Samples from three small intestinal sites were examined by light and scanning electron microscopy and quantitative data obtained from histological sections. Although the morphological appearance of the small intestine in acutely diabetic mice was similar in many respects to literature accounts for the diabetic rat, infestation with filamentous microorganisms was present in the jejunum and ileum. The quantitative data showed that these sites also contained distorted villi, fewer crypt profiles, more goblet and Paneth cell profiles and a smaller epithelial volume in comparison to controls. These findings may represent differences between the rat and mouse models of streptozotocin-induced diabetes mellitus.

Surface features of small-intestinal mucosa in childhood diarrheal disorders

The pathophysiology of diarrhea, especially in the otherwise healthy child, is still poorly understood. The aim of this study was to use the scanning electron microscope (SEM) to examine the surface of the jejunal mucosa of children with chronic nonspecific diarrhea (CNSD) (n = 9) and to compare the findings with specimens obtained from children with (n = 21) and without (n = 11) other gastrointestinal diseases. Light microscopy of the specimens from children with CNSD was normal. However, SEM showed the presence of bacterial colonization with predominantly coccoid organisms in 100% of cases. This colonization was associated with loss of glycocalyx and clumping of the microvilli. The children with celiac disease (n = 9) all showed characteristic appearances with light microscopy, but only one had bacterial colonization on SEM. The surface features of specimens from children with other gastrointestinal disorders (food intolerance, postenteritis syndrome, protracted diarrhea of infancy, and immune deficiency states) were very similar to those from the CNSD group. Bacteria were visible on 89% of specimens, and in half of these cases the organisms were bacilli. SEM of specimens from children with no gastrointestinal disease (ages 11-107 months) suggested an increased density of villi/unit area with advancing age. Bacteria were present in only two cases and did not include bacilli. The findings suggest that bacterial colonization of the surface of the small intestine is common in children with several gastrointestinal diseases and may play a part in their pathogenesis. Routine SEM examination of jejunal biopsies provides information not available from standard light microscopy, which may be relevant to the treatment of children with chronic diarrhea.

Gastrointestinal uptake and translocation of microparticles in the streptozotocin-diabetic rat

Uptake and translocation of particulates across the mucosal barrier of the gastrointestinal (GI) tract is now generally recognised but the effect of pathophysiologically induced changes on this process is less well established. This study evaluated the effect of diabetes mellitus on GI absorption of particles, comparing particle localisation and particle loading in different microanatomical sites of the primary organ (small intestine) and possible particle translocation pathways to selected secondary organs (mesenteric lymph nodes, liver, spleen) in normal and streptozotocin-induced diabetic animals. Fluorescent polystyrene latex particles (approximately 2 microns diameter) were fed orally to young adult Sprague-Dawley rats and quantitative bulk tissue and morphological techniques used to chart particle transit across the small intestine to secondary organs 0.5 h postadministration. In the normal animal, epifluorescence and confocal laser scanning microscopy provided confirmatory evidence for particle absorption within the primary organ and transport to other sites in the body. By contrast, in the diabetic animal, particle translocation and peripheral distribution were reduced with approximately 30% decrease in particle loading in the epithelial/nonepithelial tissue compartments. This could be a consequence of gastric retention and altered intestinal motility and permeability which are known to be associated with diabetes.

Early intestinal microparticle uptake in the rat

This time-course study investigates the early uptake and passage of microparticles across the intestinal mucosa. Single intraoral doses of fluorescent latex particles, 1.82 microns in diameter, were administered to young adult male, nonfasted rats at a dose of 1.88 x 10(9) particles. Peyer's patch regions and mesenteric lymph nodes were collected at 5, 15 and 30 min time points for both bulk tissue and morphological analyses. Particles were found at all experimental time points in macerated intestinal and nodal specimens: particle numbers were higher in proximal than in distal intestine at all time points despite the fact that particle numbers in distal Peyer's patch regions increased with time. Particle numbers in mesenteric lymph nodes also increased with time after administration. Detailed morphological data for several intestinal and nodal tissue compartments showed substantial early uptake of particles by villous epithelium, including goblet cells, but low involvement of follicle-associated cells. The distribution of particles in the lymph nodes confirmed that translocation occurred to all nodal compartments. These studies give confirmatory evidence that uptake and translocation of microparticles may take place as early as 5 min after administration and suggest that intestinal region may influence uptake.

Morphometric analysis of the small intestinal epithelium in the indomethacin-treated mouse

To obtain a clearer understanding of the changes which are induced in the small intestine of the mouse by an ulcerogenic dose of indomethacin, a quantitative analysis of the nonulcerated small intestinal mucosa was performed in mice that were given 2 injections of indomethacin at a dose of 85 mg/kg body weight. At 20 h after the administration of the drug, values were obtained for epithelial volume, whole crypt number, and for the number of profiles of columnar, Paneth, entero-endocrine and goblet cells and cryptal mitotic figures in the small intestine. Comparison of the values obtained from indomethacin-treated mice with those from control mice showed that there were fewer whole crypts and a reduced epithelial volume in the jejunum and ileum in indomethacin-treated mice. The numbers of columnar and Paneth cell profiles and of mitotic figures were significantly greater in the jejunal and ileal crypts in indomethacin-treated mice than in controls. These findings suggest that the administration of high-dose indomethacin in the mouse leads to crypt losses and increased mitotic activity in the nonulcerated parts of the small intestine.

The effect of size on uptake of orally administered latex microparticles in the small intestine and transport to mesenteric lymph nodes

PURPOSE

The present study examines the relationship between size and particle transit across the mucosal barrier of the gastrointestinal tract to other sites of the body. The extent of particle uptake with increasing size, the tissue distribution and cut-off points for 2-20 microns particles is investigated.

METHODS

An established fluorescent latex particle-young adult rat model is used and particle numbers in small intestine and mesenteric lymph nodes, 0.5 h post administration, counted by fluorescence microscopy in bulk tissue specimens and cryosections.

RESULTS

Bulk tissue analysis provides evidence for the presence of particles of all sizes in the Peyer's patch regions, but only for 2 microns particles in the nodal tissues. Microscopy establishes uptake of both 2 and 6 microns particles in most intestinal and nodal tissue sites and compartments. By contrast, uptake of the larger particles is much reduced.

CONCLUSIONS

Although more of the smaller (2 microns) particles are taken up, particularly by epithelial tissues, the 6 microns size appears more efficient in terms of volume translocated to lymph nodes. This could have implications in the therapeutic use of particles for drug and vaccine delivery and for radiation safety.

Uptake of yeast (Saccharomyces boulardii) in normal and rotavirus treated intestine

BACKGROUND

There has recently been a growing interest in the use of the non-pathogenic yeast Saccharomyces boulardii, in the treatment of gastrointestinal disorders, including diarrhoea. The full effects of administration of the yeast are not fully understood.

AIMS

To investigate the morphological effects of inoculated S boulardii on mouse intestinal villi, both in control animals and those treated with rotavirus.

METHODS

Seven day old BALB/c seronegative mice were intubated with either rotavirus (30 microliters orally) or S boulardii (1.5 g/kg) or both rotavirus and S boulardii administered together. Control animals were given saline only. Animals were killed by decapitation 48 hours post-treatment. The middle region of the small intestine was studied using light microscopy and transmission and scanning electron microscopy, including backscattered electron imaging.

RESULTS

Animals treated with rotavirus with or without S boulardii developed severe diarrhoea and showed morphological villous changes such as stromal separation and increased epithelial vacuolation. Specimens treated with S boulardii contained yeast particles within the mucosal tissues.

CONCLUSION

The administration of S boulardii did not influence the changes produced by rotavirus, but yeast particles appeared to be taken up by the villous mucosa, with the predominant route apparently being uptake between adjacent epithelial cells.

The effect of graft-bed irradiation on the healing of rat skin grafts

This study explores the possible side effects on healing skin grafts of irradiation, commonly used intraoperatively following surgical tumor removal. The experimental model involved the delivery of a single 10-Gy dose of electron radiation to the recipient bed of a skin wound, followed by attachment of a full thickness rat skin autograft. Skin graft repair was assessed by light microscopy, immunohistochemistry, and transmission electron microscopy over a 3-week period for grafted and grafted-irradiated groups. Graft-bed irradiation reduced fibrinogen, fibrin, and fibronectin deposition in the wound. It also produced brief changes in the extent of both re-epithelialization and granulation tissue formation, and reduced the diameter of collagen fibrils in the granulation tissue. Despite these changes, the results suggest that graft-bed irradiation only delays the healing process, producing no serious clinical complications at the time points studied.

Morphological profiles of neutron and X-irradiated small intestine

This paper describes the response of mouse small intestine, at several time points after treatment with neutron or X-irradiation, using doses expected to give similar effects in terms of crypt/microcolony survival. Using resin histology, the effects of radiation on the numbers of duodenal cell types and measurements of tissue areas were assessed. The results for individual parameters and for an estimate of overall damage are given in a data display, which summarises the morphological profile of the organ after both types of radiation. Damage and recovery were seen for many of the parameters studied but there was no standard response pattern applicable for all parameters. In particular, the response of individual crypt cell types could not be predicted from knowledge of the change in crypt numbers. With regard to the holistic response of the gut, neutron irradiation appeared to have caused more damage and produced more early effects than the X-irradiation. More specifically, neutron treatment led to more damage to the neuromuscular components of the wall, while X-irradiation produced early vascular changes.

The application of microridge analysis in the diagnosis of gastro-oesophageal reflux disease

BACKGROUND

The percentage of epithelial surface area covered by microridges (%MR) seen during scanning electron microscopy of oesophageal biopsy specimens has previously been shown to correlate with symptomatic reflux disease, a result < or = 35% being abnormal. The aim of this study was to compare %MR with endoscopy, light microscopy, and pH monitoring results.

METHODS

Sixty-seven patients with heartburn were divided into oesophagitis or none on the basis of endoscopy and light microscopy findings and into those with and without abnormal acid reflux on the basis of pH monitoring.

RESULTS

The endoscopic and light microscopic oesophagitis groups had significantly greater degrees of acid reflux than those without oesophagitis (p < 0.05), even though neither the specific %MR nor the number of patients below the 35% cutoff showed any difference between those with and without endoscopic oesophagitis, light microscopic oesophagitis or those with normal and abnormal acid reflux on pH monitoring.

CONCLUSION

Despite the significant relationship between endoscopic and light microscopic oesophagitis and abnormal pH monitoring microridge analysis did not correlate with any of these variables

Ultrastructural observations on the peritoneum in the mouse

The serous mesothelium of the serosa and mesentery of the small intestine in the mouse were examined by scanning and transmission electron microscopy. The serosa consisted of a single layer of flattened microvilli-bearing cells containing nuclei, caveolae and micropinocytotic vesicles. The observations in this study differed from previous reports on mesothelial surfaces in two respects. A surface layer of amorphous material was present over parts of the serosa. This layer probably represents serous fluid trapped by the mesothelial microvilli but is unaffected by prefixation rinsing in saline or ultrasonic cleaning. The layer is lost following osmication and routine processing for transmission electron microscopy. The possibility that a serous fluid layer may be preserved in this way may be useful in assessing changes in the peritoneum. Stomata were observed in the mesentery but there was no evidence of a connection with the lymphatic system. The presence of mesenteric stomata may explain the difference in permeability reported between parietal peritoneum and mesentery.

Cortical bone growth and maturational changes in dwarf rats induced by recombinant human growth hormone

The growth hormone (GH)-deficient dwarf rat was used to investigate recombinant human (rh) GH-induced bone formation and to determine whether rhGH facilitates simultaneous increases in bone formation and bone maturation during rapid growth. Twenty dwarf rats, 37 days of age, were randomly assigned to dwarf plus rhGH (GH; n = 10) and dwarf plus vehicle (n = 10) groups. The GH group received 1.25 mg rhGH/kg body wt two times daily for 14 days. Biochemical, morphological, and X-ray diffraction measurements were performed on the femur middiaphysis. rhGH stimulated new bone growth in the GH group, as demonstrated by significant increases (P < 0.05) in longitudinal bone length (6%), middiaphyseal cross-sectional area (20%), and the amount of newly accreted bone collagen (28%) in the total pool of middiaphyseal bone collagen. Cortical bone density, mean hydroxyapatite crystal size, and the calcium and collagen contents (microgram/mm3) were significantly smaller in the GH group (P < 0.05). Our findings suggest that the processes regulating new collagen accretion, bone collagen maturation, and mean hydroxyapatite crystal size may be independently regulated during rapid growth.

Uptake and translocation of microparticles in small intestine. Morphology and quantification of particle distribution

The intestinal transit of large (micro-) particles to other sites of the body remains a controversial issue of relevance in various fields of study. In this report fluorescent polystyrene latex microparticles in the size range of 2 microns were used as models for nonspecifically absorbed nonbiodegradable particulates. They were administered to young adult rats as a single oral dose of 1.65 x 10(9) particles; Peyer's patches and surrounding normal absorptive small intestinal tissue were collected at various time points. Quantification of solubilized tissue samples and fluorescence (epi- and confocal) qualitative and quantitative microscopy showed uptake of latex microparticles in all parts of the intestine sampled, but with the proximal segment the preferential site of absorption. The maximum uptake of particles occurred 0.5 hr after dosing in all three segments of the small intestine; there were progressively smaller numbers with distance from the pylorus and with time. Translocation of small numbers of particles to the mesenteric lymph nodes was also detected at 0.5 hr. Transmucosal passage of particles occurred primarily in the villous tissues adjacent to the Peyer's patch regions. These studies give confirmatory evidence for the uptake and translocation of microparticulates across the mucosal barrier and provide new information regarding site- and time-related effects on particle uptake and the involvement of the villous epithelium in particle translocation.

Morphological aspects of particle translocation in vivo following ingestion of the yeast Saccharomyces boulardii

Particle translocation in vivo was studied in mice using the non-pathogenic yeast Saccharomyces boulardii (SB). Seven day old BALB/c mice were given either saline (control) or 1.5 g/Kg SB (every six hours, up to 48 hours), by intubation, and killed by decapitation 48 hours post-treatment. Light and scanning electron microscopy (SEM) examination of specimens prepared from the middle intestine revealed the presence of yeast inclusions localised in the cytoplasm of enterocytes.

A morphological and microanalytical investigation into the uptake of particulate iron across the gastrointestinal tract of rats

The uptake and translocation of particulate iron across the gastrointestinal (GI) mucosa of young adult rats has been investigated using a range of morphological techniques and X-ray microanalysis (XRMA). In animals fed a suspension of iron powder constituted of metallic iron particles ranging in size from 6-9 microns down to 5-30 nm, light microscopic histochemistry has clearly revealed iron deposits within the tissues of the duodenum. Scanning electron microscopy of the duodenal tissue by back-scattered electron imaging has complemented the light microscopic observations and revealed a selective localization of iron in the villi with variation in levels of iron uptake by the mucosal cells. Ultrastructural and XRMA analysis of duodenum has established the presence of metallic iron nanoparticles within the brush border, lateral intercellular spaces of the mucosal cells, mitochondrial cristae and cytoplasm of both mucosal and stromal cells. The observations indicate that metallic iron particles, in the nano-size range, may be taken up by the GI mucosa and that the passage of such particles across the epithelial barrier may take place through both a paracellular as well as a transcytotic process.

A commentary on morphological and quantitative aspects of microparticle translocation across the gastrointestinal mucosa

It is now generally accepted that particulates in the nano-range (< 1 micron) can and do cross the intestinal mucosa. However, the issue is less well resolved for particles in the micro-range (> 1 micron) and this is discussed in relation to the variety of experimental designs present in the literature. Emphasis is placed on the relative contributions of quantitative bulk tissue analysis with respect to qualitative and quantitative morphological analysis. The discussion is extended to observations on factors influencing the particle translocation process including variation in particle uptake in relation to intestinal region and time post-dose administration based on data for uptake of -2 microns latex particles by rat Peyer's patch tissue. Although a significant body of data now identifies the intestinal processus of particle translocation it is underlined that discrepancies may arise as a consequence of different analytical approaches and that this is an issue to be addressed for valid comparisons of data.

Heavy ion induced changes in small intestinal parameters

The effects on 17 different structural parameters of mouse small intestine three days after treatment with three types of heavy ion (neon, iron and niobium) are compared, the first two being of particular relevance to space flight. The data for niobium are given in full, showing that changes after niobium ion treatment are not standard and are concentrated in the epithelial compartment, with few of the parameters having a response which is dose dependent. When comparisons are made for the three types of heavy ion, the damage is greatest after neon ion irradiation, implying that the additional non-epithelial damage produced as LET rises from X rays through neutrons to neon ions is not necessarily maintained as LET continues to rise. Further understanding is therefore needed of the balance between changes affecting the vascular and absorptive components of the organ. Variation from group to group is also important, as is variation of strain or gastrointestinal status. All such factors are important in the understanding of changes in multicellular organs after exposure to heavy ion radiation.

Electron irradiation slows down wound repair in rat skin: a morphological investigation

To date, there have been few morphological investigations of the effect of electron radiation on the healing of skin wounds in rats. The present morphological study examines the wound repair process in electron-irradiated rat skin by electron microscopy. Standardized, full-thickness, incisional wounds were made in the lower dorsal skin of animals which had been locally irradiated with 9.6 Gy electron radiation 7 days previously. The irradiation dose was maximal at 3 mm depth. Twenty-four rats were used in the investigation; 12 were irradiated and 12 sham-irradiated. Three rats from each experimental group were killed at 1, 3, 7 and 14-day time intervals after wounding. The morphological effect of electron irradiation on the repair of each wound was investigated by light microscopy (LM) and scanning electron microscopy (SEM). New granulation tissue visualized by SEM was quantified using computerized image analysis. The results suggest that a single, partial-body, controlled depth dose of electron irradiation delays wound repair. LM showed that there is a depression of the inflammatory cell and tissue exudate response, slowing of epithelial migration, and a decrease in fibroblast representation, together with a delay in the formation of collagen bundles. Granulation tissue formation was impaired up to 7 days post-wounding, but was restored to around control values by day 14, indicating that healing was delayed. However, as the healing of normal tissue was not prevented, this study supports a preoperative role for the use of low-dose electron irradiation therapy for the treatment of electron-sensitive superficial pathologies in surgical practice.

Structural and morphometric analysis of murine small intestine after indomethacin administration

Indomethacin, a nonsteroidal anti-inflammatory drug, induces the formation of gastrointestinal ulceration both in experimental animals and in humans. A study of indomethacin-induced ulcers in the mouse showed that two doses of indomethacin, each administered subcutaneously at 85 mg/kg body weight, induced well-defined gastrointestinal ulcers in C57 mice, accompanied by inflammatory and vascular changes in the stomach and small intestine. Maximal damage was observed 20 h after the second dose of indomethacin. Morphometric analysis identified changes in all compartments of the small intestine. There was a marked reduction in the length of the small intestine, intestinal dilatation, a significant decrease in villous height, with the formation of subepithelial blisters or blebs within villi, and submucosal vascular dilatation. There was no change in the number of villi or of submucosal arterioles or in the total amount of muscle present in the wall of the intestine. The tissue changes identified in this study may have implications for gut function at specific periods during indomethacin treatment.

Rabbit and human non-keratinising stratified squamous oesophageal epithelium displays similar microridge structure by scanning electron microscopy

Since the oesophageal epithelium of common laboratory animals, rats and mice, is keratinized it is unsuitable for comparison with typical non-keratinized stratified squamous human epithelium. It is thus important to find a suitable animal model for the study of human oesophageal tissue changes. This study investigated the microridge structure of immature and adult rabbit specimens, and adult human biopsies by scanning electron microscopy and morphometry. The investigation revealed a similarity between typical squamous human and adult rabbit oesophageal mucosal epithelium. While human epithelium specimens subdivided into two other groups (non-typical squamous and non-squamous); all typical squamous human biopsies were from patients who had normal endoscopy reports and no reflux symptoms. The surface cells of typical squamous human epithelium displayed complex microridge patterns (64% of cell surface) but patterns in non-typical squamous specimens were more variable (38%) (P < 0.001) and cell boundaries less obvious. Rabbit squames displayed clear microridge patterns with an elevation in the percentage of cell surface covered by microridges, with increasing age, from immature to adult specimens (P < 0.001). There was no statistically significant differences between adult rabbit, and 'typical squamous' human biopsies (range 51-65%), results which suggest potential use of a rabbit model to study changes in human oesophageal tissue.

Early effects on the morphology of mouse small intestine of single or combined modality treatment with hyperthermia and X-irradiation

This study describes the effects of hyperthermia and X-irradiation on the morphological appearance of normal, at risk tissues in the ileum of the mouse. The early morphological effects 1 day after a combined modality treatment are compared with those due to either hyperthermia or X-irradiation given alone. The response was assessed qualitatively and semiquantitatively using scanning electron microscopy and a villous scoring technique. Early post-irradiation effects on topography did not differ significantly from those observed after small intestine exteriorisation without treatment. The villous scores for the combined modality treatments reflected greater damage than would be expected from the sum of villous scores for each modality treatment on its own. This suggests that the combined modality treatment had a synergistic or enhancing effect. A 4 hour time interval between the two treatments did not seem to reduce the enhancing effect. Further studies are required to investigate the effects of fractionated combined treatment.

Relationship between villous shape and mural structure in neutron irradiated small intestine

Previous work on irradiation of mouse small intestine has assessed the changes produced by counting crypts/microcolonies, scoring villous shape or examining morphological changes in specific parts of the wall. This paper used scanning and transmission electron microscopy to study the effects of whole body irradiation with 5 Gy neutrons on the surface and internal features of the intestinal wall of CFLP mice, 1 day, 3 days and 7 days after treatment. Empirical scores from the ultrastructural findings were inserted into a Morphological Index display calculated from analytical data based on cell counts and area measurements obtained from resin histology sections. The final data display showed that the neutron irradiation produced marked structural changes in different cells and tissues by 1 day. These changes were maximal at 3 days with substantial improvement by 7 days. When this data display was compared with scores taken from scanning electron microscopy of the mucosal surface, the change in villous shape from erect fingerlike projections to lower profiles less suited to absorption was seen to correlate more with changes in the smooth muscle than with the epithelial cryptal compartment.

Radioprotectant effects of atropine on small intestinal villous shape

Previous work has shown that irradiation produces changes in small intestinal villous shape, which can be quantified using a villous scoring system applied to scanning electron micrographs. It has already been shown that reserpine, which, like irradiation, increases gastrointestinal motility, produces a similar type of villous collapse, thereby supporting the theory that this form of injury may not be due entirely to changes in the cryptal epithelial compartment, as has been assumed previously. Atropine, chosen for its ability to decrease gut motility, produces a different form of villous shape change. The aim of the current work was to investigate the ability of atropine to decrease the villous damage caused by irradiation and thereby improve the likely absorptive capacity of the small intestine. The current experiments used crypt counting, qualitative light microscopy and villous scoring techniques. Groups of unirradiated mice examined included baseline controls and those treated with atropine, sham irradiation and a combination of these two schedules. Two irradiated groups were studied, one with and one without atropine treatment. The results show that atropine given with irradiation reduces the extent of the damage to villous shape, implying that the total effect on the neuromuscular tissues is less destructive after the combined treatment. It is also of interest that atropine appears to have an additional radioprotectant effect on the radiation induced crypt depletion, implying that neuromuscular behaviour may influence this compartment, hitherto considered as dependent on epithelial proliferative capacity.

Mucosal changes in mouse duodenum after gamma-irradiation or reserpine treatment

Although the bulk of the literature implies that most of the radiation-induced effects on small intestine are related to epithelial damage, previous work has indicated that there are structural changes in the neuromuscular component of the wall. The short timescale of changes in villous shape produced by hyperthermia but similar to those seen after radiation, also supports the claim that there is a neuromuscular contribution involved. A preliminary report showed that the radiation-induced changes in the small intestine could be simulated by the administration of reserpine, a drug chosen for its effects on the neuromuscular component of the mucosal wall. A system of villous scoring indicated that the overall effects of the two regimes were approximately equivalent in terms of the changes produced in the shape of the villi. The current paper describes the results of experiments to compare the two regimes over the time scale 1 h to 3 days. The time points were chosen to include likely maximum damage caused by reserpine (18 h after treatment) and radiation (3 days after treatment). Mice were irradiated with 15 Gy gamma-rays from a 60Co source or treated with reserpine (1 mg/kg and 16 mg/kg). Scanning electron microscopy showed some changes in the duodenal mucosal topography of some control groups which may be related to the stress of treatment and are in keeping with previous findings. However, the changes seen in treated groups were greater than those found in the corresponding control samples. The overall villous changes were plotted using a grid score method, which showed that both radiation and reserpine treatment altered the villous morphology in a similar way. Light microscopy and transmission electron microscopy showed that smooth muscle damage was associated with the villous collapse. The work indicates that the intestinal wall can be damaged by many agents and that greater understanding of radiation-induced damage can be gained by comparing it with that produced in other ways.

Neutron and X-ray effects on small intestine summarized by using a mathematical model or paradigm

The responses of intestinal tissues to ionizing radiation can be described by comparing irradiated cell populations qualitatively or quantitatively with corresponding controls. This paper describes quantitative data obtained from resin-embedded sections of neutron-irradiated mouse small intestine at different times after treatment. Information is collected by counting cells or structures present per complete circumference. The data are assessed by using standard statistical tests, which show that early mitotic arrest precedes changes in goblet, absorptive, endocrine and stromal cells and a decrease in crypt numbers. The data can also produce ratios of irradiated: control figures for cells or structural elements. These ratios, along with tissue area measurements, can be used to summarize the structural damage as a composite graph and table, including a total figure, known as the Morphological Index. This is used to quantify the temporal response of the wall as a whole and to compare the effects of different qualities of radiation, here X-ray and cyclotron-produced neutron radiations. It is possible that such analysis can be used predictively along with other reference data to identify the treatment, dose and time required to produce observed tissue damage.

Rat small intestinal morphology and tissue regulatory peptides: effects of high dietary fat

Sprague-Dawley rats (3 weeks old) were fed on isoenergetic diets in which 40% of the total energy was provided as fat either in the form of butter (high saturated fat), olive oil (high monounsaturated fat) or maize oil (high polyunsaturated fat), with one group on low-fat (10% of total energy) standard diet as a control. Animals were killed after 8.4 (se 0.8) weeks by cardiac puncture. Similar pieces of jejunum and ileum were prepared for morphometric studies. Extracts of tissue from the proximal and distal segments of the whole small intestine from four animals per group were assayed using established techniques for enteroglucagon, motilin, neurotensin, somatostatin, substance P and vasoactive intestinal peptide (VIP). We found that maize oil and olive oil increased villus height: crypt depth ratio in both jejunum and ileum. Maize oil increased tissue concentrations of somatostatin (P less than 0.05) and substance P (P less than 0.005) in the proximal segment. Both maize oil and olive oil increased tissue concentrations of neurotensin and substance P (P less than 0.005) in the distal segments. These observations may explain the improvement of intestinal absorption of fluid following supplementation with polyunsaturated fat.

Familial expansile osteolysis: a morphological, histomorphometric and serological study

Biopsies from the diseased bones of patients with familial expansile osteolysis (FEO) were examined by light and electron microscopy. Focal concentrations of multinuclear osteoclasts were present, and these contained viral-like microcylindrical inclusions which appeared exclusive to their nuclei. No consistent relationship was found between osteoclast size and the number of osteoclast nuclei containing microcylindrical inclusions. Quantitative histomorphometry showed evidence of increased bone remodelling with high bone cell densities and a decrease of the reversal period in bone remodelling. The lesions contained prominent woven bone and fibrovascular tissue, together with mononuclear cells and adipocytes. Little bone was found in the most radiolucent lesions, which were almost totally occupied by adipocytes and fibrovascular tissue. Serology did not reveal any significant differences between the viral antibody titres of patients and their age- and sex-matched controls. The present study suggests that intranuclear viral-like microcylindrical inclusions of osteoclasts are not a specific feature of Paget's disease, and are found in other disorders of osteoclast function, including pycnodysostosis, osteopetrosis, giant cell tumours, and familial expansile osteolysis.

Early morphological changes in blood capillaries of mouse duodenal villi induced by X-irradiation

The mouse has been used extensively as a model for radiobiological studies. In particular, the cellular compartments of the intestinal villi have been examined, in an effort to gain an understanding of the gastrointestinal disturbances which follow radiotherapy of the abdomen. The response of the blood vessels has been, however, largely neglected. This paper examines the early response of the duodenal capillaries to an X-ray dose of 10 Gy using conventional light and transmission electron microscopy. The villous capillaries were examined at 6 h, 1 day and 3 days after treatment. The results showed that the capillaries responded to X-irradiation within 6 h. exhibiting marked vasodilation similar to that observed in acute inflammation. Significantly there was no ultrastructural evidence of endothelial cell disruption or loss of junctional attachment between the cells, but the characteristic fenestrae of these vessels were less apparent than in the controls. One day after treatment the capillaries had become constricted, with many vessels totally non-patent. The cytoplasm and nuclei of the endothelial cells showed changes consistent with vascular damage, such as nuclear shape alterations and luminal cytoplasmic projections. Three days after treatment there was variation in the capillary patency, as some vessels showed signs of incipient necrosis whilst others were relatively normal in appearance. The results suggest that the early vascular response typically involves a phase of vasodilation followed by constriction within the first 24 h after treatment, a finding consistent with the radiation response of skin capillaries in what has been described as 'transient erythema'. The ultrastructural changes associated with the phasic changes in patency did not suggest large scale endothelial death, but rather alteration of the functional capacity of the vessels which may in turn affect the other cell populations in the villi.

Exudate variation in the rabbit gastrointestinal tract: a scanning electron microscope study

The mucosal exudate from the gastrointestinal tract of six adult female New Zealand rabbits was studied using scanning electron microscopy and without any attempt being made to clean the luminal surface before screening. The exudate consisted of mucus, debris and bacteria. Qualitative assessment showed that the nature and distribution of exudate varied along the length of the gastrointestinal tract from the oesophagus to the anal canal, with little variation from animal to animal. Bacterial counts for rod-shaped bacteria were carried out on areas randomly selected from the upper, middle and lower oesophagus and the oesophageal-cardiac junction. The degree of bacterial colonisation was found to decrease along the length of the oesophagus from upper to lower parts, but it was increased at the oesophageal-cardiac junction. This assessment was not undertaken in the other regions of the gastrointestinal tract as the mucosal surface areas could not be easily measured owing to their undulating nature. The study indicates the variability of the mucosal exudate, which should be recognised as part of the true interface between ingested food and the cell surface along the gastrointestinal tract.

Collared crypts in irradiated small intestine

Crypts of Lieberkuhn are radiosensitive: the technique of crypt counting is an established method of assessing radiation induced changes in the small intestine. However, there has been little work done on the surface contours of the crypts, as they open into the intervillous cleft. The current paper describes the structure of control mouse crypt mouths as unobtrusive openings approximately 5 microns in diameter. After radiation with heavy ion particles, the crypt mouths are substantially larger (up to 10 microns in diameter) with a marked collar which is similar to that sometimes seen in coeliac disease. The shape and incidence of the collared crypts is described for specimens irradiated with neon, silicon and iron ions, with treatment with iron producing the most marked collars: it is suggested that the size and incidence of the collared crypts may be related to the LET of the beam used. It is of interest that the abnormal crypts are not produced after single doses of X-irradiation. The consideration of the structure of the collared crypts may require a redefinition of the terms crypt and villus with priority being given to the position of subepithelial vessels rather than surface shape. Finally, although the collared crypts can not be directly equated with 'tunnel' or 'channel' lesions, it is pointed out that they do represent localised damage with a specific position and shape.

An investigation of vanishing bone disease

Vanishing bone disease is a rare condition producing local deformity and instability. Fibrovascular tissue replaces bone completely but the mechanism of bone destruction and resorption is unknown and there is controversy regarding the presence or absence of osteoclasts in the disease. Radiography, clinical chemistry, light microscopy, transmission electron microscopy (TEM) and cytochemistry were used to investigate the condition of a young woman presenting early in the disease process. We detected atypical ultrastructure in osteoblasts and endothelial cells. The rare osteoclasts, numerous mononuclear phagocytes and vascular endothelium found in the condition reacted positively for the enzyme acid phosphatase. Aggressive local excision of diseased tissue and insertion of a free vascularized bone graft at an advanced stage of the disease, accompanied by subsequent radiotherapy for residual disease only were successful in rehabilitating the affected forearm and hand.

Radiation induced changes in the blood capillaries of rat duodenal villi: a corrosion cast, light and transmission electron microscopical study

Disturbances of gastrointestinal function are an important limiting factor in radiotherapy of the abdominal and pelvic regions. The pathogenesis of radiation induced intestinal dysfunction is not completely understood, although the intestinal mucosa has been shown to respond to irradiation by a progressive reduction in villous size. Since blood vessels in other organs have been implicated in the initiation of post-irradiation changes, the present study examines the response of villous blood vessels to an X-ray dose of 10 Gy after 3 days. Vascular corrosion casts and light and transmission electron microscopy (TEM) were used to study the post-irradiation vascular response. In control and sham-irradiated animals, the villous plexus was fountain-like: an arteriole entered the villous base and divided apically into two terminal branches. Villous capillaries apparently derived from the terminal branches, and united to form venules. In capillary loops the vertical inter-capillary distance was greater than the horizontal inter-capillary distance. After irradiation, the vessels became tortuous and the plexus was compressed apico-basally, shown by a decrease in the vertical inter-capillary distance. The capillary luminal diameter, as measured on resin semi-thin sections, was significantly increased. TEM showed that the endothelium was irregular and there was evidence of plasma leakage. These results suggest that villous damage seen after irradiation can include changes in the villous vasculature.

Internal structure of the intestinal villus: morphological and morphometric observations at different levels of the mouse villus

The internal structure of the mouse jejunal villus was examined from apex to base in transverse serial sections. The villi were arbitrarily divided into apical (1-160 microns), middle (161-320 microns) and basal (321-480 microns) thirds. Histological and ultrastructural morphometry was performed on villous epithelium, stroma, blood vessels and lacteals at the three levels. The cross sectional area and the number of cells/section increased apico-basally in both the villous epithelium and the stroma, but the increase was greater in the latter. The enterocytes in the villous basal third were narrow and had oblong nuclei. The enterocytes gradually became wider and their nuclei attained a more round or oval shape towards the villous apex. The microvilli of these cells also increased in length from the villous base to apex. Although the number of capillaries/section was approximately the same at the three levels examined, it appeared that the apical third was relatively more vascular if the overall apico-basal increase in the villous size was taken into consideration. The villi had a single lacteal, whose cross sectional area generally increased towards the villous base. The results of this study indicate that the internal structure of the intestinal villus is not uniform along its length. Therefore, it is important that when studying normal and abnormal villi, like should be compared with like so as to ensure that the normally occurring variations in the villous morphology are not confused with those induced by disease or experimental processes.

Examination of mucosal surfaces by scanning electron microscopy before and after removal of debris

A rapid method is described whereby gastrointestinal biopsy specimen surfaces can be examined by scanning electron microscopy with overlying tract contents (debris) intact, and also re-examined after cleaning to determine the structure of the underlying mucosal surface. The conductive coating of gold is removed using mercury, a non-wetting agent. The specimen surface is suitably cleaned of debris after a brief ultrasonication in absolute ethanol which mixes with the transitional fluid (CO2) used for critical point drying.

Radiation-induced changes in mouse duodenal papilla

Radiation-induced changes in duodenal mucosal morphology as seen by scanning electron microscopy have been widely reported in the literature. However, no comment has previously been made on any post-irradiation alteration in the duodenal papilla. This paper describes the preliminary results of an investigation into the effects of X rays on the papilla. The duodenal papilla was difficult to find in untreated and sham irradiated mice. It was identified in only two of six mice examined and was located 5.37 and 4.43 mm from the gastroduodenal junction. Eighteen hours after irradiation with 15 Gy X rays, there was little change in position or prominence of the papilla. However, 3 days after treatment, the papilla was only 2.19-3.83 mm from the pylorus. It was also more prominent, being found in all three animals studied and having a widely dilated orifice in contrast to the closed structure seen in the unirradiated specimens. It is concluded that treatment with X rays alters the structure of the duodenal papilla. There may be implications for duodenal function in this marked change in the papilla, which controls the flow of pancreatic and biliary secretions.

Topographical variation in the mucosal surface of oesophageal biopsies

There have been comparatively few scanning electron microscopic (SEM) studies of mucosal biopsies of the human upper gastrointestinal tract. This study reviews the use of SEM in human oesophageal research and deals with the results of a SEM study of thirty two biopsies of human oesophagus, taken from eighteen patients during endoscopy for upper gastrointestinal symptoms. For each biopsy, three areas of the mucosal surface chosen at random were examined using standard magnifications. The SEM showed three mucosal patterns, which were designated typical squamous, atypical squamous and nonsquamous, each displaying common features in relation to desquamation, cell boundaries and microridges. The two squamous epithelial groups showed surface microridges. The typical group displayed clear cut cell boundaries and well developed microridges arranged in rows. The atypical squamous group showed desquamation, less well developed cell boundaries and variation in microridge patterns. Many nonsquamous specimens displayed simple columnar epithelium, similar to mucosa of gastric type. Care was taken to correlate the surface structure of the oesophagus with the endoscopic appearance. The two assessments were done independently and the material was coded throughout. The broad subdivision of the biopsies into groups using these qualitative topographical criteria gave good correspondence with the endoscopic appearance.

Development of villous damage in mouse small intestine after local hyperthermia or irradiation

Damage to mouse small intestine has been assessed in the period up to twenty-four hours after heating a portion of the gut for 20 min at 43 degrees C and also in the period up to nine days after 10 Gy/whole body X-irradiation. The surface changes and the light microscopic appearances after the two types of treatment were described. The damage was evaluated using scores produced by assessing villous collapse as seen with a scanning electron microscope (SEM). Maximum damage was seen two hours after hyperthermia and was more pronounced in antimesenteric portions of the same specimen. Maximum damage was observed three days after X-irradiation. Despite the difference in the time scale and severity of development of surface changes after the two types of treatment, the structure of the damaged and recovering villi looked similar, except for the apical extrusion of the enterocytes immediately following the heat treatment.

Microplication patterns on human buccal epithelia following radiotherapy: a scanning electron microscopic analysis

Surface topographical detail in human buccal smears of normal and irradiated tissue have been studied with scanning electron microscopy. Cells collected by buccal smearing show patterns of microplicae and microvilli, although such detail is occasionally masked by mucus and to a lesser extent by debris and bacteria. Buccal smearing permits collection of numerous specimens with little discomfort to the patient, but requires caution in identification of superficial and deep cell layers and of upper and lower surfaces. The analysis of specimens derived in this way shows that variations in the pattern of surface microplicae reflect the radiotherapeutic regimes of the patients from which they were obtained. Straight parallel microplicae characteristic of normal control and pre-irradiated specimens were absent in specimens collected during early irradiation treatments (between 24-48 Gy), but instead were present as short discontinuous ridges and microvillous projections. At the highest levels of radiation treatment (54-60 Gy) cells exhibited small areas devoid of any surface projections in addition to a range of normal and early irradiated microplicae patterns. From these results it is suggested that the patterns of microplications and microvilli on cell surfaces can be used to obtain information on the state of the stratified squamous epithelium from which they come.

Morphological criteria for comparing effects of X-rays and neon ions on mouse small intestine

Several techniques have been used to assess changes in different parts of mouse small intestine three days after a single dose of either 16.5 Gy X-rays or 11 Gy neon beam. The doses were chosen to be approximately equivalent in terms of their effect on the number of microcolonies present. In qualitative terms, villous damage was seen after both types of radiation exposure: collared crypts, similar to those seen in biopsies taken from patients suffering from coeliac disease, were conspicuous after neon irradiation. In semi quantitative terms the doses used, although estimated from previous work to give biologically equivalent damage, produced a greater drop in microcolony numbers after X-irradiation. This makes all the more important the fact that significantly greater changes were seen after neon irradiation-a greater drop was seen in the number of villous profiles and the number of goblet cells per villus. There was also greater breakdown in the integrity of the villous basement membrane. Different responses after the two types of irradiation are therefore seen in the cryptal and villous compartment. Progress is being made towards identifying and quantitating radiation induced changes in different populations of cells or tissues in the small intestine.