A histopathological study of hearts and spleens of hamsters (Mesocricetus auratus) infected with Leptospira interrogans, serovar pyrogenes.

The effects of Leptospira interrogans on the heart and spleen of hamsters were studied histopathologically. Infected hamsters were sacrificed at 1 hour, 6 hours and on days 1, 2, 3, 4, 5 and 6 after inoculation with Leptospira interrogans serovar pyrogenes. The heart and spleen of each of the sacrificed animals were removed and processed for routine conventional light microscopy. Infected hearts showed degenerative change of the cardiac muscle cells composed of cellular swelling, condensation of chromatin granules, pyknotic nuclei and acidophilic cytoplasm. Congestion of the cardiac blood vessels and hemorrhagic areas were found. Necrosis of the cardiac muscle cells was surrounded by numerous inflammatory cells. In the spleen, cellular necrosis was found scattered throughout the splenic cord. The splenic sinusoids were dilated and congested with many hemorrhagic areas. Inflammatory cell infiltration was also noted in the splenic parenchyma and the splenic sinusoids.

The ultrastructure of the gravid uterus of Brugia pahangi, another rich source of antigen of the filarial parasite.

The gravid uterus with zygotes and microfilariae in utero of Brugia pahangi, a rich source of antigen as revealed by a recent immunofluorescent technique, were studied ultrastructurally. The epithelial cells of uterus show ultrastructural features of synthetically active cells. Their secretions may provide nutrients for the egg in utero. On the basal side, the uterine epithelial cells may also secrete substances to form the basal lamina of the uterus which is rather thick and irregularly fused with the basal lamina lining the body wall where the pseudocoelomic cavity is obliterated. For the most part, the uterine basal lamina contains uniform granular material of moderate electron density. There are also elongated visceral muscle cells embeded in it, and which surround the uterus, with adjacent cells overlapping. The gravid uterus contains several stages of developing microfilariae within its lumen, the cleaving zygotes are also present at another level. The morula of zygotes are composed of several closely packed cells surrounded loosely by their own egg shell membranes. The egg shell becomes more convoluted as development proceeds. The egg shell surrounding the developing microfilariae in utero is secreted by the uterine epithelium. This structure later becomes the sheath of circulating microfilariae, and is highly antigenic as indicated by intense labeling with fluorescent antibodies.

The possible antigenic sources of brugia pahangi.

The antigenic sources of adult and the third larval (L3) stages of Brugia pahangi were detected by indirect immunofluorescent technique. Six panels of antisera were used, including human antisera against Brugia malayi and Wuchereria bancrofti, cat antisera against B.malayi and B.pahangi and jird antisera against B.malayi and B.pahangi as primary antibodies. All antisera gave the same results, although four of the six were not infected by B.pahangi. This indicates non-species specificity, and B.pahangi, B.malayi and W.bancrofti must share most of the common antigenic molecules. All antisera reacted well with the surface of L3 B.pahangi in the whole mount preparation. This indicates non-stage specificity. The most intense fluorescence was located at the epicuticle, the basal lamina lining the body wall, the gut and the reproductive tract, the egg shell in utero and the sperm. The hypodermis, the muscle cells, the cuticle beneath the epicuticle, the epithelial cells of the gut and the reproductive tract showed moderate fluorescence. The least fluorescence was observed in the egg interior.

The development of rabbit embryo’s heart : Serial sections of 4-14 mm rabbit embryos compared to a 10 mm pig embryo.

Serial sections of 4-14 mm rabbit embryos were carefully studied in relation to the serial section of 10 mm pig embryos under a light microscope in order to compare the development of the heart and related blood vessels. The heart of the 4-14 mm rabbit embryo has incompletely divided chambers comprising two atria and two ventricles. The partition of the atrium by the septum primum can be seen at the 4 mm stage and still incompletely attaches to the endocardial cushion even at the 12 mm stage. The rupture of the septum primum brings about the communication between the two atria, the foramen secundum, can be seen only at the 12 mm stage. Communication between the two ventricles is also via the interventricular foramen. The right atrium receives venous blood from the right horn of the sinus venosus which is larger than the left side. The bulbus cordis communication with the right ventricle and brings blood to the aortic sac which extends branches to the branchial arches to join the right ventricle and brings blood to the aortic sac which extends branches to the branchial arches to join the dorsal aorta. The heat of the rabbit embryo is very similar to that of the pigembryo. The pig embryos are easy to obtain for slide preparation, there will be no problem in using rabbit embryos for the study of the development of the heart.

A Microanatomical study of the organs of hamsters (Mesocricetus auratus) infected with Leptospira interrogans, serovar pyrogenes which caused an outbreak in Thailand 1999.

The effects of Leptospira interrogans on various organs of hamsters were studied microanatomically. Three infected hamsters were sacrificed at 1 hour, 6 hours and on days 1, 2, 3, 4, 5 and 6 after infection with Leptospira interrogans serovar pyrogenes. The kidneys, lungs, liver, gastrocnemius and hamstring muscles of all the sacrificed animals were removed and processed for routine conventional light microscopy. The microscopic change of the infected kidney showed degenerative changes of the renal tubular cells, including vacuolar degeneration, cellular swelling of proximal tubules, dilatation of the distal tubular lumen and necrosis. The glomeruli had many pathological appearances including congestion and swelling of the glomerular tuft, imflammatory cell infiltration, hemorrhage in the glomerular tuft and the urinary space. This phenomenon may have been related to glomerular damage. Congestion of the renal blood vessels was demonstrated in both the cortex and the medulla. There were many other hemorrhagic areas including the interstitium and the renal tubule. Interstitial nephritis and pyelonepritis were also found. In the lung, the alveolar and interalveolar capillaries were distended and engorged with red blood cells. A small number of alveoli were filled with inflammatory cells which represented bronchopneumonitis. Most areas of the lungs showed intersitital and intra-alveolar hemorrhage as well as thickening of the alveolar septum. The interalveolar septum was also thickened by accumulation of inflammatory cells which is a sign of interstitial pneumonitis. The infected liver showed enlarged and vacuolated hepatocytes being related to cloudy swelling the hepatocytes. Vascular and sinusoidal congestion, prominent Kupffer cells, and inflammatory cell infiltration in the hepatic parenchyma and hepatic sinusoids were also demonstrated. The portal area showed a number of inflammatory cells. Hepatocellular necrosis was found scattered throughout the hepatic lobules which is a sign of hepatocellular damage and disorganization of the liver structure and function. In the gastrocnemius and hamstring muscles, dilation and congestion of blood vessels was shown in some hamsters in the infected groups. The congestion of blood vessels is a sign of hyperemia. One hamster of the infected group showed inflammatory cell infiltration in the perimysium of the gastrocnemius muscle. Another one showed necrosis of some muscle fibers together with inflammatory cell infiltration which are signs of muscular inflammation. The results of this research correspond with previous similar studies, however, the pathogenesis of this study was quicker and the infection was more severe than in other studies. This may be due to the difference in serovar studied.