The effect of green pit viper (Trimeresurus albolabris) venom on platelet morphology by electron microscopy

The incidence of venomous snake bites increases every year in Thailand, especially due to green pit viper. After the bite, there is bleeding due to thrombin-like property of the venom. The mean platelet volume has been reported to be decreased in those who have been bitten by this snake. In this study we investigate the effect of green pit viper venom (Trimeresurus albolabris) on platelet volume (MPV), number and morphology of platelets in vitro. The test was carried out by washing platelets in phosphate buffer at pH 7.2 to remove fibrinogen, then the washed platelets were mixed with green pit viper venom. Platelet morphology was examined by scanning electron microscope (SEM). The morphology of platelets was smaller than normal which ranges from 1.1- 1.2 microm. Green pit viper venom can directly effect platelet morphology, decreasing platelet volume.

Solitary rectal ulcer. Electron microscopy study of two cases

Two cases of solitary rectal ulcer syndrome occurred in an 18-year-old woman and a 24-year-old man. Each had a history of bleeding on defecation, together with constipation alternating with diarrhea. In each case, a solitary rectal ulcer was noted by sigmoidoscopy and confirmed by both light and electron microscopic evaluations of biopsy material. Both clinical and pathologic features of these cases are compatible with classic rectal ulcer syndrome, which has been suggested to result from trauma followed by an ischemic event leading to fibrosis of the mucosa. Fibrosis in these two cases was confirmed by electron microscopy.

Pigmentary glaucoma: an ultrastructural study

Trabeculectomy blocks from both eyes of a patient with pigmentary glaucoma were examined by light microscopy, SEM, and TEM. Evidence of a development angle anomaly was not found. The pigment granules packed within the trabecular meshwork were probably responsible for the glaucoma in this disease. Evidence suggested that melanin granules may contain a large amount of protein, unsaturated lipid, or both.

Ocular microcirculation. Scanning electron microscopic study

A simple vascular casting technique utilizing a low-viscosity plastic was used to study the three-dimensional ocular microcirculation of the cat eye. Vascular arrangements in different anatomic areas of the eye, i.e., iris, ciliary body, retina, optic nerve, and choroid, were clearly elucidated by scanning electron microscopy. This modified technique is described in detail, and scanning electron micrographs are presented to illustrate the reliable results.

An ultrastructural study on a new type of hepatic perisinusoidal cell in fish

A new type of perisinusoidal cell containing numerous microfilaments is described for the first time. It is found in abundance in the livers of both marine and freshwater fish. These perisinusoidal cells are situated within the space of Disse and adhere firmly through desmosomes both to sinusoidal endothelial cells and to hepatocytes. The cytoplasmic microfilaments are striking and make these cells readily distinguishable from the perisinusoidal fat-storing cells of Ito. Although the function of these cells is not known, the observations presented here suggest that they may provide a supportive framework within the liver.

New observations on the fine structure of the liver in goldfish (Carassius auratus)

A re-examination of goldfish liver was made through the use of SEM of fractured samples and TEM of ultrathin-sections and freeze-etch replicas. Several new hepatic fine structures described in the present study are morphologically similar to those reported previously in many higher vertebrates including mammals. Hepatic sinusoids of goldfish contain fenestrations which are arranged into sieve plates. Although the hepatic plates are made up of two layers of hepatocytes, the parenchymal cells of gold fish liver are morphologically similar to mammalian hepatocytes, particularly with respect to the sinusoidal surfaces which are studded with numerous microvilli. The intercellular surfaces of hepatocytes have both nexus and demosomal junctions, similar to those found in various epithelial cells of higher vertebrates, between the openings of the intracellular bile canaliculi and the intralobular bile ductules which are situated in the center of the bicellular hepatic plate.

Ultrastructure of cells cultured on polycarbonate membranes

A method is described for preparing undisturbed cell cultures for both scanning and transmission electron microscopy. Cells were propagated on polycarbonate membranes with pores of 0.2 micrometer or less. Cultured cells together with their supports were prepared for both scanning electron microscopy and transmission electron microscopy using routine methods. For transmission electron microscopy a rapid schedule of infiltration and polymerization was used. The method described in this report yielded good results and it allowed the fine structure of cultured cells to be viewed in situ by both scanning electron microscopy and transmission electron microscopy.

Surface features of cirrhotic liver

The surface features of single cells and of multicellular tissue units in cirrhotic rat livers have been studied by scanning electron microscopy (SEM). Cirrhosis of the liver was produced in rats by simultaneously treating them with carbon tetrachloride and sodium phenobarbital. Connective tissue septa consisted of a losse mesh-work of fibers in which fibroblasts were embedded. The arrangement and surface features of hepatocytes in cirrhotic nodules differed from those found in parenchyma of normal livers. Hepatocytes in cirrhotic nodules universally formed plates two cells thick. The portion of the hepatocyte surface covered by microvilli was greatly increased in cells from cirrhotic livers, and this was reflected in a corresponding reduction in the area occupied by the smooth-surfaced narrow intercellular space. Canaliculi between hepatocytes in cirrhotic livers were reduplicated and frequently branched. hepatocyte surfaces covered by microplicae and flattened microvilli, typical of connective tissue-facing surfaces in normal livers, were greatly increased in cirrhotic livers corresponding to the increase in connective tissue. Where hepatocytes directly contacted fibroblasts (and not fibers), their surfaces were entirely smooth. Sinusoidal endothelial cells in cirrhotic livers contained only isolated, relatively sparse pores, and they lacked both sieve plates (pore complexes) and large fenestrations.

Effect of hepatic venous outflow obstruction on pores and fenestration in sinusoidal endothelium

The ultrastructure of pores and fenestrations in hepatic sinusoidal endothelial cells was examined following partial surgical occlusion of the suprahepatic portion of the inferior vena cava. Within 12 h after partial obstruction of hepatic venous outflow, endothelial pores (less than 0-1 mum in diameter) and sieve plates in the distal halves of sinusoids were greatly reduced in number or were totally absent, and they were replaced by large fenestration (less than 1-0 mum in diameter). These results suggest that pores forming sieve plates may fuse to form large fenestrations. The findings also indicate that sinusoidal hypertension and hypoxia associated with obstruction of hepatic venous outflow alter the distribution of pores and fenestrations in sinusoidal endothelium

Scanning electron microscopy of normal rat liver: the surface structure of its cells and tissue components

Scanning electron microscopy (SEM) allows the surface ultrastructure of intrahepatic cells and other tissue components of liver to be delineated. Excellent depth of focus of the SEM makes it possible to visualize surfaces of intact cells in their native configurations. This report details the surface characteristics and inter-relationships of hepatocytes and hepatic plates, sinusoidal endothelial cells and sinusoids, presumed Kupffer cells, vessels, bile ducts, connective tissue, and the capsule of rat liver. Hepatocytes present three structurally distinctive faces--the intercellular face containing flat surfaces and bile canaliculus, the sinusoidal face, and the connective tissue face which abuts portal tracts and hepatic veins. Sinusoidal endothelium is penetrated by large (1 to 3 mum) and small (0.1 mum) fenestrae, the latter occurring in clusters of up to 50. The width of bile canaliculi and distribution of large fenestrae vary proximodistally along hepatic plate or sinusoid. The cells of portal bile ductules contain microvilli located in linear rows and sparse cilia. Endothelium of hepatic artery and of portal vein is sparsely fenestrated.