Ghrelin and obestatin in thyroid gland - immunohistochemical expression in nodular goiter, papillary and medullary cancer

INTRODUCTION

Previous studies analyzing ghrelin and obestatin expression in thyroid gland tissue are not unanimous and are mostly related to ghrelin. The role of ghrelin and obestatin in the thyroid gland appears very interesting due to their probable involvement in cell proliferation. Furthermore, since the thyroid gland is associated with the maintenance of energy balance, the relationship between ghrelin, obestatin and thyroid function is worthy of consideration. The aim of the study was to assess ghrelin and obestatin immunocytochemical expression in nodular goiter (NG), papillary cancer (PTC) and medullary cancer (MTC).

MATERIAL AND METHODS

Analyzed samples included 9 cases of NG, 8 cases of PTC and 11 cases of MTC. The analysis of ghrelin and obestatin expression was performed by use of the immunohistochemical (IHC) EnVision system and evaluated with filter HSV software (quantitative morphometric analysis).

RESULTS

Quantitative ghrelin expression in MTC cells was higher than in NG (p = 0.013) and correlated negatively with the size of the tumor (r= -0.829, p < 0.05). We did not observe any differences in ghrelin expression neither between MTC and PTC nor between NG and PTC. Obestatin immunoexpression pattern in all analyzed specimens was irregular and poorly accented. The strongest immunoreactivity for obestatin was demonstrated in NG. In MTC obestatin expression was significantly weaker than in NG and PTC (p < 0.05 in both cases). In NG the intensity of obestatin immunostaining was significantly higher than that of ghrelin (p = 0.03). Conversely, ghrelin expression in MTC was definitely more evident than obestatin immunoreactivity (p < 0.01). There was no statistically significant difference between ghrelin and obestatin expression in PTC. No correlations were detected between reciprocal tissue expressions of ghrelin and obestatin in the analyzed specimens of NG, PTC or MTC.

CONCLUSIONS

The differences between ghrelin expression in NG and MTC suggest that ghrelin may be involved in thyroid cell proliferation. The differences between ghrelin and obestatin immunoreactivity in benign and malignant thyroid tumors could support the theory of alternative transcription of the preproghrelin gene and independent production of ghrelin and obestatin.

Immunocytochemical indicators of apoptosis in gingival tissues of patients with chronic periodontitis

Introduction. Inflammatory mechanisms of chronic periodontitis (CP) may be linked to various forms of disturbances in apoptosis.Aim. The study aimed at comparison of tissue expression of anti-apoptotic protein (Bcl-2) and proapoptotic proteins (p53, caspase-3) in gingival tissues of 30 patients with CP and of 15 with healthy periodontium.Material and methods. Gingival samples (n = 68) were obtained during the open curettage procedure with gingivectomy of adult patients (18 women and 12 men) with CP. Classical immunocytochemical (IHC) method was used to detect apoptotic proteins, and the obtained expression was evaluated using semi-quantitative IRS scale.Results. No differences could be revealed in expression intensity or reciprocal correlations between apoptotic proteins within the group of patients with CP. Greater expression of the two apoptotic proteins (Bcl-2 and p53) were detected in patients with CP than in control individuals. Moreover, a more pronounced expression of Bcl-2 was demonstrated in gingival samples of patients with localised form as compared to generalised form of CP. Expression of caspase-3 (effector phase of apoptosis) manifested no differences between CP and control individuals. Greater expression of the anti-apoptotic protein Bcl-2 and caspase-3 was detected in cells of inflammatory infiltrates in lamina propria than in keratinocytes.Conclusions. In CP significant alterations developed in expression of indicators of apoptosis, with prevalence of Bcl-2 and p53 expression, as compared to the control. The localised form of CP was linked to higher proportion of Bcl-2-positive cells of inflammatory infiltrates, suggesting that apoptosis was inhibited mainly in this form of CP. The comparable expression of caspase-3 in gingival cells with CP and in control and absence of correlation with clinical data suggested that the process of apoptosis did not play a significant role in destruction of periodontium tissues in CP.

Cytokeratin 8 and 18 tissue expression in gallbladder mucosa of patients with cholelithiasis

Cytokeratins (CKs) 8 and 18 are normally expressed in simple epithelia. This unique pair of CKs is believed to be involved in hepatic diseases and many human cancers. Little is known about the role of tissue expression of both CKs in patients with cholelithiasis (CH). The aim of the study was to analyse tissue expression of CK8 and 18 in the specimens of gallbladder mucosa in 35 young (up to 25 years of age) and 20 older patients (approximately 50 years of age) with CH. An immunocytochemical ABC method and the spatial visualization technique were conducted. Our study demonstrated significantly lower amounts of both CKs in young patients, as compared to older patients. The higher cellular expression of CK8 in older patients was linked to acute clinical course vs. chronic ones. Tissue expression of neither CK correlated with inflammatory activity (grading) of the gallbladder mucosa. A positive correlation between reciprocal expressions of the two CKs may confirm a cytoprotective role of the two proteins in both groups of patients with symptomatic CH. Significantly higher expression of CK18 than that of CK8 in younger patients suggests a different role of CK8 and 18 in lithogenesis in this group.

The effect of extracellular substance components on the proliferation and expression of hormones in cultured cells of medullary thyroid carcinomas

The effects were examined of selected extracellular medium (ECM) components on the proliferation of medullary thyroid carcinoma cells and on the production of calcitonin and CGRP. Human TT cells and rat rMTC cells were cultured for 24, 48 and 72 hours on glass coated with type I collagen, fibronectin or poly-D-lysine. More pronounced proliferation was demonstrated by TT cells grown on poly-Dlysine or collagen in comparison with the control and less pronounced proliferation was typical of cells grown on fibronectin. On the other hand, rMTC cells were more markedly manifest on any ECM substrates than that on glass. Alterations in the proliferation were paralleled by changes in the expression of CT and CGRP.

Expression of cytokines (TNF-alpha, IL-1alpha, and IL-2) in chronic hepatitis C: comparative hybridocytochemical and immunocytochemical study in children and adult patients

Hepatitis C virus (HCV) is one of the principal causes of hepatitis, which in more than 80% of cases leads to chronic lesions in the liver and involvement of extrahepatic organs. It remains unknown why the infection so frequently turns chronic, independently of patient age. Using immunocytochemistry (IHC) and in situ hybridization (ISH) (both linked to the ImmunoMax technique) we examined cell sources of TNF-alpha, IL-1alpha, and IL-2 in control and HCV-infected children and adults. We demonstrated augmented expression of all the cytokines in HCV-infected patients compared to controls. No differences were detected in amounts of studied transcripts or cytokine proteins between biopsies taken from HCV-infected children and adults. Expression of TNF-alpha was localized mainly in liver sinusoidal cells (macrophages, endothelial cells). A high proportion of hepatocytes demonstrated expression of TNF-alpha, IL-1alpha, and IL-2. In both groups of patients, higher amounts of cytokine proteins than studied transcripts were demonstrated. The augmented expression of TNF-alpha, IL-1alpha, and IL-2 in liver with a similar proportion of involved cells (mainly hepatocytes) in children and in adults points to participation of the cytokines in the pathogenesis of chronic hepatitis C. The expression is insufficient to terminate the infection and may be linked with the comparably frequent chronic transformation of HCV infection noted in children and adults.

The effect of calcitriol and its analogues on proliferation and hormone expression in cultured cells of thyroid medullary carcinomas

The study aimed at evaluating the effects of calcitriol and of its analogues on the proliferation of TT and rMTC cells (human and rat line tumour cells originating from thyroid medullary carcinoma) and at examining the effects of the substances on the secretion of the principal hormones of the cells, calcitonin (CT) and calcitonin gene-related peptide (CGRP). Cells of thyroid medullary carcinoma (human TT cells and rat rMTC cells) were cultured for 5 days in the absence or in the presence of calcitriol and of its two analogues (PRI-1906 and PRI-2191) in concentrations of 10(-9) to 10(-6) M. Calcitriol and the applied analogues weakly inhibited proliferation of thyroid medullary carcinoma in in vitro conditions. The evident effect of analogues on hormone secretion points to their effect on the process of CT gene expression.

The expression of selected neuroendocrine markers and of anti-neoplastic cytokines (IL-2 and IL-12) in lung cancers

We have continued our studies by detecting three markers of neuroendocrine tumours of the lungs, including chromogranin A, NSE and synaptophysin, to confirm the neuroendocrine origin of lung tumours and by examining the content of two anti-neoplastic cytokines, IL-2 and IL-12 in the tumours. The studies were performed on paraffin sections of lung carcinoids (n = 13) and small cell lung carcinomas (SCLC) (n = 15). Pronounced expression of all 3 markers of neuroendocrine tumours was detected in most of the pulmonary carcinoids and in 5/15 of SCLC. Co-expression of the two cytokines (IL-2 and IL-12) in tumour cells was detected in 12/13 patients with lung carcinoid and expression of at least one cytokine in 12/15 patients with SCLC. Significantly lower numbers of cells immunoreactive to both cytokines were detected in SCLC as compared to lung carcinoids. The studies have confirmed the literature data on the lowered secretion of IL-2 in SCLC and extend the data by supplying information on the expression of IL-12. The lowered expression of the two cytokines at the time of diagnosis may represent a prognostic factor for survival in SCLC.

Development of innervation in primary incisors in the foetal period

Sections from the frontal part of the mandible of 43 human foetuses from 9 to 39 weeks of prenatal age, which contained two, three and sometimes four lower incisors were immunohistochemically examined using protein gene product and neuron specific enolase (NSE) antibodies in order to establish the time of appearance of nerve fibres in the developing tooth germ and to define their topography. Nerve fibres were first detected in the dental follicle in the 11th week of intrauterine life. Their presence in the dental papilla was confirmed in the 18th week when the first layers of dentine and enamel were deposited. In the 24th week of intrauterine life, the nerve fibres first reached the subodontoblastic region. In the subsequent weeks, an increase in the number of nerve fibres accompanying blood vessels in the central portion of the dental papilla resulted in the formation of neuro-vascular bundles. Moreover, the progressive deposition of enamel and dentine was accompanied by branching of papillary nerves, which thereby formed a fan-pattern. In the foetal period, no evidence was found for the formation of a subodontoblastic plexus. However, we did observe single nerve fibres in close proximity to the odontoblast layer at the end of intrauterine life. Nerve fibres were not detected in either predentine or dentine throughout foetal life.

Immunolocalization of PTHrP in prepubertal and pubertal testis of European bison

The present study deals with immunohistochemical localization of PTHrP in prepubertal and pubertal testis of European bison. PTHrP immunoreactivity was observed in germinal cells in the testis of both prepubertal and pubertal animals. In calves, PTHrP was found in germinal cells, in seminiferous tubules lacking the lumen. The reaction was strong and regularly distributed within the cytoplasm. In adult animals, the reaction showed differentiation in spermatogenic cells. Some cells were strongly and diffusely stained, others exhibited weaker reaction of granular pattern. Sertoli cells and Leydig cells were PTHrP-negative in calves and adult animals.

Expression of mRNA for cytokines (TNF-alpha and IL-1alpha) in human cytomegalovirus (HCMV) and hepatitis B virus (HBV) infections

The study was aimed at detecting cellular sources of transcripts for two cytokines, TNF-alpha and IL-1alpha in infection with human cytomegalovirus (HCMV) or hepatitis B virus (HBV). The studies were performed on paraffin sections of organs (liver, pancreas, spleen, lungs) obtained upon autopsy from a child deceased due to acute inborn HCMV infection, on paraffin sections of liver biopsy, obtained from a child with HCMV-induced chronic hepatitis, and of liver biopsies obtained from children with chronic type B hepatitis (n = 13). The classical in situ hybridization was applied with digoxygenin-labeled probes and amplification by the ImmunoMax technique. In HCMV infection, the most pronounced expression of mRNA for TNF-alpha and Il-1alpha was detected in pancreatic islets (mainly in beta cells) and, then, in a decreasing sequence, in liver (in macrophages and sinusoidal endothelial cells) and in lungs (in alveolar macrophages). No expression of the two cytokines was detected in the spleen. In HBV infection, weak expression of TNF-alpha and more intense expression of IL-1alpha in the liver were observed, mainly in sinusoidal endothelial cells and in macrophages as well as in hepatocytes. These results were confirmed by immunocytochemical experiments.

Comparison of PTHrP expression in the epididymis of juvenile and adult European bisons

The aim of the present study was to compare the expression of PTHrP in the epididymes of adult European bisons, and 12- and 5-month-old calves. The highest PTHrP expression was observed in adult animals in muscle cells and endothelium of large vessels, and in muscle cells of the epididymal duct. In one-year-old calves, the reaction was weaker than in adult bulls, being the weakest in 5-month-old calves. However, in small vessels of adult animals, in vascular cells and smooth muscle cells the reaction for PTHrP was considerably weak, being weaker in one-year-old calves, and negative in 5-month-old calves. A similar trace reaction was observed in muscle cells of the epididymal duct in 5- and 12-month-old calves. The present study has revealed that PTHrP expression in vascular and extravascular smooth muscle cells and endothelial cells in European bison is correlated with the animal age and size of the organ.

Immunocytochemical analysis of the tissue location of cytokines (IL-2 and IL-12) in neuroendocrine lung cancer

The study aimed at immunocytochemical evaluation of the cellular expression of two cytokines, IL-2 and IL-12 in lung carcinoids (n = 10), following the earlier demonstration of two markers of endocrine tumours (chromogranin A and NSE--neuron-specific enolase). In the immunocytochemical studies the classical avidin-biotinylated peroxidase (ABC) technique was used. Results of the tests were semiquantitatively appraised employing the IRS scale. In 9/10 cases intense reaction (score: 6-12 points) was noted for both lung neuroendocrine markers. In all cases of carcinoma co-expression of IL-2 and IL-12 was demonstrated in cells of the tumours. The cytokines showed a cytoplasmic localisation of mean (score: 3-4 points) or high (score: 6-12 points) intensity of reaction. Our studies point to a possible role of the two cytokines in the proliferation of lung neuroendocrine carcinomas but more detailed analysis is required on a broader material.

Detecting the replication of the hepatitis B virus using the ImmunoMax technique following treatment with interferon-alpha in children with chronic hepatitis

BACKGROUND

Children with HBV in Poland are treated with preparations of interferon-alpha (IFN-alpha). The continuing lack of complete response to this type of anti-viral therapy remains to be explained. The application of cell biology techniques to identify the viral components in situ makes it possible to clarify the association between the distribution of the virus and morphological injury to the liver, the immune response of the host, and clinical symptoms in the natural course of infection. Our study was intended to evaluate HBV expression in liver biopsies taken an average of two years after completion of IFN-a therapy in 10 children with serological markers of persistent HBV infection.

MATERIAL/METHODS

For the immunocytochemical detection of HBcAg and for the hybridocytochemical detection of HBV-DNA, the avidin-biotin-peroxidase (ABC) technique was employed, as well as classical in situ hybridization, both additionally amplified using the ImmunoMax technique. HBcAg and HBV-DNA levels were estimated using a semiquantitative technique.

RESULTS

Our study demonstrated persistent active replication of HBV in the liver in all examined children. A mixed pattern of HBcAg localization prevailed (noted in cell nuclei, cytoplasm and cell membranes) with a somewhat lower proportion of involved cells and a more evident membrane localization of HBcAg, as compared to results obtained before treatment. HBV-DNA was observed in the cytoplasm of a fraction of hepatocytes similar to that noted before therapy.

CONCLUSIONS

The ImmunoMax technique was found to be highly suitable for in situ monitoring of HBV replication after termination of IFN-a treatment. Children with focal distribution of HBcAg and HBV-DNA have the potential for earlier eradication of the virus from their livers.

Correlation of morphological alterations of light and electron microscopy in chronic type B and C hepatitis

Chronic type B and C hepatitis involves inflammatory lesions of a variable intensity and variably advanced fibrosis. Considering current, progressively growing requirements for correct evaluation of lesions in liver biopsies, an attempt was made to appraise suitability of selected techniques for a broadened histopathological diagnosis. The lesions were evaluated at the level of light and electron microscopy. Material for the study consisted of liver biopsies obtained from adults and children (n = 60) with serological markers of chronic type B or type C hepatitis. Routine techniques of staining for light and electron microscopy, as well as the techniques of Brachet and Feulgen, were applied. HBcAg expression and HBV-DNA detection in children with chronic type B hepatitis were studied employing the avidin-biotin peroxidase complex (ABC) technique and in situ hybridisation with the ImmunoMax signal amplification. Slight or moderately intense inflammatory lesions (grading of 1 to 2 points) and a low level of fibrosis advancement (staging of 1 to 2 points) prevailed in the material, independently of the etiologic agent involved and age of the patient. Both in children and in adults, extensive lesions in the nuclear chromatin represented the common trait of chronic type B and type C hepatitis examined by light microscopy. Ultrastructural patterns confirmed the lesions and demonstrated virus-resembling particles in the cell nuclei. In HCV infection, hepatocyte cytoplasm contained tubular and horseshoe-shaped structures with lesions of mitochondria, while in HBV infection Dane's particles and tubular forms of HBsAg were detected. For cognitive reasons and due to frequently equivocal literature data, our data on ultrastructural lesions in chronic type C hepatitis seem to be of particular interest. Using the ImmunoMax signal amplification, we were able to diagnose HBV infection under light microscope and to define stage of the infection. Their sensitivity, specificity and relatively short time required for performing the tests makes them advisable in the routine diagnosis of the two infections.

Immunocytochemical localization of PTHrP in human and rat salivary glands

Parathyroid hormone-related protein (PTHrP) was isolated from tumours and is thought to represent the main factor responsible for humoral hypercalcaemia, which accompanies neoplastic diseases. At present, the protein is known to reside in multiple tissues and organs of both humans and animals. Our study was aimed at demonstrating the presence of PTHrP in normal salivary glands (parotid and submandibular) of rats and humans. Application of immunocytochemical techniques permitted to document the presence of PTHrP in the human and in the rat salivary glands. In all cases, an intense reaction was observed in intra- and interlobular ducts. In rat salivary glands, PTHrP was also present in cells of mucous acini. In our opinion, the presence of PTHrP in the ducts indicates participation of the protein in electrolyte transport across the epithelial cells. The positive reaction noted in mucous acini of rat salivary glands may indicate accessory role of PTHrP in the secretory processes in the glands.

Cellular expression of TNF-alpha in human cytomegalovirus (HCMV) infection

Human cytomegalovirus (HCMV) belongs to the most frequent human pathogens. Even if the respective pathomorphological patterns are known in detail, the mechanisms which lead to persistence of the virus in its latent form, its reactivation as well as mechanisms of cell death in the symptomatic infection remain to be clarified. It is postulated that HCMV controls expression of TNF-alpha gene and the associated secondary inflammatory response. On the other hand, TNF-alpha has been shown in in vitro studies to represent a potential stimulator of HCMV major IE promoter. The present studies have been aimed at evaluation of TNF-alpha expression in HCMV-infected brain, liver, kidney and pancreas, obtained upon autopsy from children deceased due to an inborn HCMV infection. In situ hybridisation using digoxigenin-labelled oligonucleotide probe demonstrated the expression of TNF-alpha transcript in the liver (in macrophages and endothelial cells) and in pancreatic islets of Langerhans (in beta cells). Immunocytochemical studies aimed at detection of TNF-alpha protein in the material yielded negative results.

Immunolocalization of PTHrP in the European bison and pine vole testis and epididymis

The present study deals with immunohistochemical localization of PTHrP in European bison and pine vole testis and epididymis. PTHrP immunoreactivity was observed in spermatogenic cells of seminiferous tubules in European bison and pine vole testis, with the strongerst reaction occurring in spermatozoa of pine vole testis and epididymal duct. We also observed PTHrP expression in vascular smooth muscle of epididymis and testis in both animal species, as well as slightly weaker reaction in endothelial cells of European bison epididymis. PTHrP was also expressed in the smooth muscle of the epididymal duct in European bison and pine vole. In conclusion, PTHrP is a multifunctional peptide showing both paracrine and autocrine action. Its presence in vascular endothelium and smooth muscle of testis and epididymis is connected with the regulation of vascular muscle tone, thus affecting blood flow in the vessels. PTHrP expression depends on a number of local factors. Moreover, we suppose that PTHrP also contributes to the proliferation and differentiation of spermatogenic cells.

Detection of DNA, mRNA and early antigen of the human cytomegalovirus using the immunomax technique in autopsy material of children with intrauterine infection

The present study focuses on the immunomax technique in association with the avidin-biotin-peroxidase complex (ABC) technique and a non-isotopic variation of in situ hybridisation (ISH) for optimal microscopical detection of human cytomegalovirus (HCMV). The studies were performed on an archival paraffin material originating from five children deceased due to intrauterine infection. The results of immunocytochemical and hybridocytochemical studies, with or without amplification using biotinylated tyramine, were compared with the routine histopathological results and results obtained using the polymerase chain reaction (PCR). Early antigen (EA)-HCMV was demonstrated in approximately twice as many cells as detected in the routine staining and also in cells that seemed morphologically intact. The hybridocytochemical studies confirmed the presence of HCMV DNA in cells that were positive in the immunocytochemical tests and, in addition (using the ISH-immunomax technique), in cell nuclei of intact myocardial myocytes. In general, fewer cells manifested the presence of HMCV mRNA than the presence of HCMV DNA. The immunomax technique was found to be more sensitive than the techniques of classical immunocytochemistry or of ISH. The former technique permitted the documentation of a higher number of HCMV replication sites than could be detected using the latter techniques. However, the clinical course of HCMV infection or the cause of death of the children was not directly related to the intensity of HCMV expression in tissues.

Studies on tissue expression of HBV in children with chronic hepatitis type B using Immunomax technique

The study aimed at employing the Immunomax technique to detect the markers of HBV replication (HBcAg and HBV-DNA) in liver biopsy material, obtained from children with chronic hepatitis type B. In line with the currently modified classification of chronic hepatitis and with the increasing potential of antiviral therapy it seemed purposeful to supplement routine staining techniques with studies at the molecular level. Our studies demonstrated the effective detection of both the core antigen and HBV-DNA in liver tissue in children using immunocytochemical techniques and in situ hybridization, amplified with the Immunomax technique. HBcAg was detected in 26 out of 27 liver biopsies from patients with chronic hepatitis type B and with replication of the virus. HBV-DNA was detected in all study children with HBV infection and in 2 out of 5 cases of chronic hepatitis of a distinct etiology. No significant relationships could be found between the detection of tissue HBV markers on the one hand and the intensity of inflammatory lesions or severity of fibrosis on the other.

Immunocytochemical localisation of PTHrP (parathormone-related peptide) in myoepithelial cells of human sweat and parotid glands

PTHrP is a HHM-inducing peptide. It exhibits certain structural similarity to PTH and the two hormones may act through the same receptors. PTHrP is known to be produced in various tissues as well as during development. In this study we decided to immunocytochemically demonstrate PTHrP in normal skin and squamous cell carcinomas as well as in parotid glands (normal, inflamed and neoplastic). In the skin, PTHrP expression was demonstrated in epidermis and in smooth muscle cell layer of blood vessels. In squamous cell carcinomas, the expression was noted in foci of keratinization. In parotid glands, the peptide was localised in excretory ducts and in blood vessels, while inflammation of the gland and its tumours resulted most frequently in the less intense immunoreaction. The results are consistent with those of other authors. The novel observations include demonstration of PTHrP expression in myoepithelial cells of sweat glands and in parotid glands, where it may be involved in the control of their contractile activity.

Polyhormonal aspect of the endocrine cells of the human fetal pancreas

Histological studies were performed on 30 pancreases obtained from normal human fetuses aged between the 9th and 38th week. For immunocytochemistry, the avidin-biotin-peroxidase method was used to identify and colocalise insulin, glucagon, somatostatin, pancreatic polypeptide and proliferating cell nuclear antigen. In the 9th week, cells containing all investigated peptides were present. During the fetal period, two populations of endocrine cells have been distinguished, Langerhans islets and freely dispersed cells. The free cells were polyhormonal, containing insulin, glucagon, somatostatin and pancreatic polypeptide, and were localised in the walls of pancreatic ducts throughout the whole gland. During the development of the islets we have observed four stages: (1) the scattered polyhormonal cell stage (9th-10th week), (2) the immature polyhormonal islet stage (11th-15th week), (3) the insulin monohormonal core islet stage (16th-29th week), in which zonular and mantle islets are observed, and (4) the polymorphic islet stage (from the 30th week onwards), which is characterised by the presence of monohormonal cells expressing glucagon or somatostatin. Bigeminal and polar islets also appeared during this last stage. The islets consisted of an insulin core surrounded by a thick (in the part developing from the dorsal primordium) or thin rim (part of the pancreas concerned with the ventral primordium) of intermingled mono- or dihormonal glucagon-positive or somatostatin-positive cells. The most externally located polyhormonal cells exhibited a reaction for glucagon, somatostatin and pancreatic polypeptide. Apart from the above-mentioned types of islets, all arrangements observed in earlier stages were present. Proliferating cell nuclear antigen-positive cells (single in the large islets and more numerous in the smaller ones) were predominantly observed in the outermost layer. Taken together our data indicate that, during the human prenatal development of the islet, endocrine cells are able to synthesise several different hormones. Maturation of these cells involved or depended on a change from a polyhormonal to a monohormonal state and is concerned with decreasing proliferative capacity. This supports the concept of a common precursor stem cell for the hormone-producing cells of the fetal human pancreas.

Proliferating-cell nuclear antigen (PCNA) in the human adrenal glands at the end of the embryonic period

Studies were performed on adrenal glands of 7 human embryos between 6 and 8 weeks of intra-uterine life using clone PC-10 mouse serum (Dako, No. M879). During the 6th week, immunoreactivity for the proliferating-cell nuclear antigen (PCNA) was observed only in the central and medial parts of the developing fetal zone of the adrenal gland (75.2 +/- 3.1% of adrenocortical cells showed nuclei stained with anti-PCNA), while the peripheral part was immunonegative. One week later the second outer layer, i.e. the permanent cortex appeared. During the 8th week, the cortex formed two distinct zones: a relatively large and centrally located fetal zone and a thin rim of definitive (permanent) cortex, the later adult adrenal cortex. PCNA-positive cells were present throughout the surface of the gland being most numerous in the center (76.4 +/- 1.4%) and less numerous in the peripheral part (16.6 +/- 2.6%). A very thin layer of permanent cortex surrounding the fetal zone showed less numerous cells stained for PCNA (36.4 +/- 3.4%) as compared with the inner fetal zone. During the 8th week the proliferative cells activity was similar in both zones. The middle proliferative center of the fetal zone disappeared, and all cells of this zone had similar PCNA reactivity.

Prenatal development of the human pancreatic islets. Immunocytochemical identification of insulin-, glucagon-, somatostatin- and pancreatic polypeptide-containing cells

Histological studies were performed on 24 pancreases of normal human embryos and fetuses aged 7 to 38 weeks. For immunocytochemistry, the avidin-biotin-peroxidase method was used to identify and localize insulin, glucagon, somatostatin, and pancreatic polypeptide (PP) cells. In 7 wk old embryos, cells containing somatostatin and PP are observed. One week later appear single glucagon-positive cells. In the 9th wk, insulin producing cells are visible. During the fetal period two populations of the investigated cells are found: Langerhans islets and dispersed cells. The latter cells containing insulin, glucagon or somatostatin are localized in the walls of pancreatic ducts throughout the whole gland, while PP-positive cells are seen mainly in the part of the pancreas, which develops from the ventral anlage (anteroinferior part of the head and adjacent part of the main pancreatic duct). During the development of islets we have observed four stages: (1) scattered cells (7 to 10 weeks); (2) grouping cells (11 to 15 weeks); (3) mantle and zonular islets (10 to 29 weeks), in which B cells located inside are surrounded by a thick zone of A, PP and somatostatin-producing cells; (4) mixed islets (from 30 weeks on) - all cells are scattered over the whole transverse section of the islet. In the developing pancreas, the glucagon- and somatostatin-containing cells are the most numerous, while the insulin and PP-containing cells occur in lesser quantities.

Immunocytochemical characterization of two thyroid medullary carcinoma cell lines in vitro

The immunocytochemical characterization of cell lines originating from thyroid medullary carcinoma, i.e. human TT cells and rat rMTC 6-23 cells, was undertaken. The immunocytochemical studies were supplemented by ultrastructural studies, including ultrastructural immunocytochemistry, and by radioimmunological estimation of calcitonin secretion to the medium. In rMTC 6-23 cells (subcultures 24 to 30), no hormone presence was demonstrated immunocytochemically, which corresponded to the absence of secretory granules at the ultrastructural level. Of various proteins sought, only neuron-specific enolase could be demonstrated. Nevertheless, the cells secreted calcitonin into the medium. TT cells (passages 145 to 160) produced secretory granules. The granules contained calcitonin, calcitonin gene-related peptide, somatostatin, neurotensin, met-enkephalin, leu-enkephalin, gastrin releasing peptide, parathyroid hormone-related protein, functional proteins of the chromogranin group and synaptophysin. Other functional proteins found in the cytosol of TT cells included non-specific enolase, calbindin and tyrosine hydroxylase. Receptor for calcitriol was localized in the cell nucleus. Marker proteins were localized in the cytosol (carcinoembryonic antigen) and in the cell skeleton (alpha-tubulin, cytokeratin). Following changes in ionized calcium levels in the medium, changes in calcitonin secretion and in immunocytochemical detectability of some hormones and functional proteins were observed. TT cells demonstrated the expression of numerous hormones and functional proteins associated with calcitonin secretion. Further, the cells in their ultrastructure, immunocytochemical and secretory characteristics, resemble more closely normal parafollicular cells of the thyroid and, in our opinion, represent a more appropriate model for functional studies.

Hybridocytochemical and immuno-ultrastructural study of calcitonin gene expression in cultured medullary carcinoma cells

The study was aimed at a morphological demonstration of calcitonin (CT) gene expression in cultured TT cells, or, more specifically, hybridocytochemical detection of CT mRNA and calcitonin gene-related peptide (CGRP) mRNA and ultrastructural localization of the two hormones. The TT cells originated from medullary carcinoma of human thyroid gland. Ultrastructural studies of TT cells demonstrated a well-developed rough endoplasmic reticulum, large Golgi apparatus and low number of secretory granules. Hybridocytochemical studies showed the presence of mRNAs for CT and CGRP in all TT cells. At the ultrastructural level, double immunolabelling demonstrated that the two hormones were always expressed together in the same secretory granules. Our results provide a significant addition to the biochemical studies performed up to now and indicate that all TT cells produce both mRNAs and both hormones in parallel.