Spatiotemporally differential expression of HER (human epithelial growth factor receptor)-2 with sexual dimorphism in submandibular gland of mice

SUMMARY: Considering that the submandibular gland (SMG) of postnatal mice performs active cell proliferation, apoptosis and differentiation which are regulated by proto-oncogene products in cancerous cells, the expression and localization of a proto-oncogene product HER (human epidermal growth factor receptor)-2 was examined in SMG of postnatal mice. In Western blot analysis, the expression for HER-2 was high until pre-puberty, and it decreased from puberty to young adult stages with male SMG more dominant. In immunohistochemistry, the immunoreactivity was positive in acinar and ductal cells of newborn SMG with distinct localization at the intercellular apposition sites. The immunoreactivity in acinar cells progressively decreased to negligible levels by pre-pubertal stage, while it remained positive in most ductal cells throughout the postnatal time-course. The immunoreactivity in cells of terminal tubules and intercalated ducts, both of which have a high potential to produce cells, were seen at levels similar to those of more proximal ducts, while the immunoreactivity in ductal basal cells was significantly high, but the granular convoluted tubule cells were seen at negligible levels in male and at faint levels in female. In immuno-electron microscopy of excretory ducts, the immunoreactivity was dominantly localized on the basal infolding membranes as well as vesicles and vacuoles of various sizes, but rarely in Golgi apparatus and mitochondria. The immunoreactivity without association to any membranous structures were also seen, though not numerous. The relation of expression levels of HER-2 in various portions of normal SMG to those in their cancerous ones is briefly discussed.

RESUMEN: Considerando que la glándula submandibular (GSM) de ratones postnatales realiza la proliferación celular activa, apoptosis y diferenciación que están reguladas por productos protooncogénicos en células cancerosas, la expresión y localización de un producto protooncogénico HER (receptor del factor de crecimiento epidérmico humano) - 2 se examinó en GSM de estos ratones. En el análisis de Western blot, la expresión de HER-2 fue alta hasta la prepubertad, y disminuyó desde la pubertad hasta las etapas de adultos jóvenes con GSM macho más dominante. En inmunohistoquímica, la inmunorreactividad fue positiva en las células acinares y ductales de GSM de recién nacido con una localización distinta en los sitios de aposición intercelular. La inmunorreactividad en las células acinares disminuyó progresivamente a niveles insignificantes en la etapa prepuberal, mientras que permaneció positiva en la mayoría de las células ductales durante el transcurso del tiempo posnatal. La inmunorreactividad en las células de los túbulos terminales y los conductos intercalados, los cuales tienen un alto potencial para producir células, se obser- vó a niveles similares a los de los conductos más proximales, mientras que la inmunorreactividad en las células basales ductales fue significativamente alta, pero en el túbulo contorneado granular las células se observaron en niveles insignificantes en los machos y en niveles débiles en las hembras. En la microscopía inmunoelectrónica de los conductos excretores, la inmunorreactividad se localizó de manera predominante en las membranas de pliegues basales, así como en vesículas y vacuolas de varios tamaños, pero raramente en el aparato de Golgi y en las mitocondrias. También se observó la inmunorreactividad sin asociación a ninguna estructura membranosa, aunque no numerosa. Se discute brevemente la relación de los niveles de expresión de HER-2 en varias porciones de GSM normal con aquellos en sus cancerosos.

Cleidocranial dysplasia in a Thai cadaver.

A rare cleidocranial dysplasia or Marie-Santon syndrome1 was seen in a man who devoted his body for anatomical study of medical students in faculty of Medicine Siriraj Hospital. It was shown that there were typical bony anomalies of this disease in his body. According to his family history, he was diagnosed as cleidocranial dysplasia. Until now he had transferred these characteristics to his two next generations; two sons, one daughter and one nephew. This disorder might have a strong genetic inheritance.

The study of the transverse sections of 7-10 somite chick embryos by the scanning electron microscopy and compared with the classical light microscopy.

Objective: To comparatively study the use of scanning electron microscopy and conventional light microscopy of the transverse sections of the 7-10 somite staged chick embryos as model for the study of development of human embryo. Methods: Conventional light microscopy and scanning electron microscopy had been applied as tools for the study of the chick embryos. Results: The results showed that scanning electron micrographs gave the clearer different views of chick embryo transverse sections as compared with the conventional light microscopy. Conclusion: From this study it was clearly shown that the three dimensional images obtained from scanning electron microscope could give comprehensive view of chick embryo specimens. Hence this should be the good alternative way for Embryology study.

Povidone – iodine induced changes in the cyst of Acanthamoeba spp.: transmission electron microscopic study.

Objective: This study was to investigate morphological changes and fine structures of the cyst form of Acanthamoeba after treatment with various concentrations of povidone – iodine (BetadineTM) using transmission electron microscopy. Methods: Acanthamoeba spp. were isolated from patients with amebic karatitis and obtained from the cultures on 3% non-nutrient agar (NNA) plates seeded with heat killed Escherichia coli (NNA-E coli) with incubation at 30°C for 7 days. The cysts were harvested and washed in ameba saline solution and adjusted to a final concentration of 104 cysts/ml. Various concentrations of povidone-iodine were put in the microtiter plate wells. The minimum cysticidal concentration was the lowest concentration that there was no excystment after 1 week of incubation. The cysts were prepared for routine transmission electron microscopy to determine the structural and organelle damages. Results: Structural damages were observed in the cysts treated with povidone-iodine of 0.04% dilution. Many cysts showed shrinkage of amoeba from the cyst wall and there was a slight withdrawal of the cytoplasm from the cyst wall. Many cysts were ruptured and broken into small pieces. Conclusion: Structural damages were observed in the cysts treated with 0.04% dilution of povidone-iodine solution or more than that. The damage started with pores produced in the cyst wall and the loss of water, shrinkage and loss of the cytoplasm of the inside cell from the cyst wall, followed by breaking of the cyst wall and the inside cell into small pieces.

The ultrastructure of the parathyroid gland in cadaveric embalmed specimens.

Objective: This study is to observe ultrastructurally of the parathyroid gland from cadaveric embalmed specimens by light microscopy and by transmission electron microscopy. Methods: The parathyroid glands were carefully dissected from the posterior surface of thyroid glands of the cadavers of the Department of Anatomy, Faculty of Medicine Siriraj Hospital, Mahidol University. Each parathyroid was bisected into two, one put into 10% formaldehyde and the other to the 2.5% glutaraldehyde. The first group was prepared for routinely HE staining for light microscopy. The one which the specimen with the best preserved was chosen to prepare for the TEM. Results: The parathyroids of the cadavers were all well preserved as viewed by light microscopy. They are all reviewed the chief and oxyphil cells which easily distinguishable. The chief cells are more numerous and acquired the characters of actively synthesis of materials. These are the basophilic cytoplasm and large clear nucleus. The oxyphil cells are less numerous and acquired its characters of larger cells, red cytoplasm and dense dark nuclei. When viewed by TEM, it is cleared that the cells are well preserved. The chief cells are characterized by large heterochromatic nucleus and the cytoplasm is filled with the secretory vesicles, some of which the RER and the Golgi apparatus can be observed. Conclusion: The human tissue from the cadavers of the Department of Anatomy, Faculty of Medicine Siriraj Hospital was well preserved even viewed by TEM. This may be due to the fact that the fixative was pushed through the great vessels until it circulated throughout the blood vessels of the whole body. Especially the endocrine glands such as the parathyroids which were richen in blood supplies, the fixative might be forced through the capillary sinusoid and then this tissue is highly preservation.

Pollen grains in stool examination may lead to misdiagnosis for the parasite ova: 3 case reports.

Three cancer patients were admited in Siriraj Hospital for chemotherapy. Routinely, the blood, the urine and stool examination have to be done for checking up / excluding other diseases. In the stool examinations of these patients, light microscopically revealed abundant oval-shaped organism-like structures. They looked like the ova stage of several parasites which could not give the diagnosis by the light microscopic level. Therefore the ultrastructural examination was performed by scanning and transmission microscopes. The TEM revealed clearly that they were not of animal structure because their walls were made up of plant tissue - cellulose. They were concluded to be the pollen grains of plants by comparing to the figure and description from textbooks of palynology, the study of pollen grains. They may be the pollen grains of the herbal medicine which were consumed by the cancer patients as an alternative treatment of the cancer. If light microscopic level cannot give the exact diagnosis, electron microscopy may be helpful.

The ultrastructure of the secretory cells of the human carotid body.

Objective: The purpose of this study was to study the ultrastructure of the human carotid body by using transmission electron microscopy. This is to distinguish the secretory cells of the human carotid body and classify the cells by the characteristic size, shape and electron density of the secretory granules, since nowadays there is still no data about TEM of the human carotid body. There is also no report about the exact secretions of the organ. Methods: 4 carotid bodies at the carotid bifurcations were identified and dissected from 2 fresh cadavers. The specimens were prepared for routinely TEM. Results: There are at least 3 secretory cell types in the human carotid body accordings to TEM. The cells were classified by the characteristic size, shape and the electron density of the secretory granules. The type I has large clear membrane bound granules, type II has small electron dense membrane bound granules and type III has large moderately electron dense membrane bound granules while type IV is thought to be the degranulated form of the type I. Conclusion: There are at least 3 types of secretory cell in the human carotid body and there may be 3 types of secretion as well. The immunocytochemical technique will be performed in future to identify the secretions.

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.

Development of the heart in 4-12 mm golden hamster embryo.

The developing heart in this study is focused on serial sections of 4-12 mm golden hamster embryos, which were stained with hematoxylin and observed under a light microscope, compared to 10 mm pig embryos. The developing hearts of Golden hamster and pig embryos are very similar. Although the partition of the hamster’s heart is still incomplete, it is clearly divided into four chambers. Two atria are separated by septum primum which grows ventrally but does not reach the endocardial cushion; the foramen primum still remains in the 4 mm stage. This is just a very minor difference compared to that of the 10 mm pig embryo. This foramen is later closed at the older stage. Two ventricles are incompletely separated by the interventricular septum, remaining the interventricular foramen. The ventricle is connected to the bulbus cordis and truncus arteriosus, draining blood to the aortic sac. This study indicates that the developing heart of a golden hamster embryo can be used as a laboratory model instead of that of a pig embryo in order to study the development of a human heart. This will solve the problem of insufficient pig embryos and maintain the efficacy in the study embryology.

Development of the face.

The human face develops between the fourth and eighth week after conception. Its development can be traced to five facial primordia appearing around the stomodeum in the fourth week. They are, namely, one frontonasal prominence, two maxillary and two mandibular prominences. Two nasal placodes develop on each side of the lower part of the frontonasal prominence at the end of the fourth week and further develop into the medial and lateral nasal prominences. The early development of the human face is similar to that of other mammals, such as pigs, rats and rabbits; all of which acquire branchial arches in the early stage of development. The rabbit branchial arches develop at the 4-5 mm stage and nearly disappear at the 12-14 mm stage, as the second one grows dorsally and obliterates the cervical sinus. The medial and lateral nasal prominences appear at the 4-5 mm stage. At the 12-14 mm stage the nasal cavities are more extensive than those of a 10 mm pig embryo and are of the same stage of development as a 15 mm pig embryo. Currently, we use 10 and 15 mm pig embryos as models in this study of human facial development. However, in the future, it will be more suitable to use 4-12 mm rabbit embryos because they are obtained more easily.

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 development of the rabbit eye.

Serial sections of the rabbit embryos measuring 4-14 mm. were carefully studied to compare the developing eye with 36 somites chick embryos and 10-15 mm. pig embryos. The eyes of the 4-5 mm. rabbit embryos were at an earlier stage than those of the 36 somites chick embryos, but at about the same stage as the fifth-week human embryos. At this stage, the optic cups had already formed but some of the lenses had incompleted double fusion. The eye of the 12-14 mm. rabbit embryos were somewhat identical to the 15 mm. pig embryos and can be compared to the sixth week human embryos. At this stage the optic cups were divided into the outer pigment and inner nervous layers; the lens was characterized by a thinner anterior lens epithelium and the longer posterior lens fiber. The mesenchyme surrounding the optic cups of this stage showed a slight condensation to from the vascular and fibrous coats of the eyeball. The rabbit embryos of 4-14 mm. were more suitable for use as laboratory models in studying eye development than of the pig embryos since the latter were no longer available for slide preparation.

The development of the ear of rabbit embryo.

The ear consists of three parts which are different origin but function as one unit. The internal ear originates from the surface ectoderm covering the lateral sides of myelencephalon at the fourth week. This ectoderm thickens to from the otic placode and then invaginates to form the otocyst and splits from the surface ectoderm. The otocyst or otic vesicle divides into 2 parts, the ventral cochlear and the dorsal utricular portions. The cochlear gives rise to the saccule and the cochlear duct while the utricular portions gives rise to the uteicle, semicircular ducts and endolymphatic duct. These epithelial structures so formed are known as the membranous labyrinth. The bony labyrinth and the perilymphatic space originate from the mesenchy otic capsule. The middle ear, consisting of the tympanic cavity and the auditory tube, are lined with epithelium of the endodermal origin of the first pharyngeal pouch. The ear ossicles, the malleus and incus are derived from the first and the stapes from the second arch cartilages. The external auditory meatus develops from the first pharyngeal cleft, while the tympanic membrane originates from the mesenchyme between. In order to understand ear development, pig and chick embryos were used in the laboratory studies. Since the pig embryos are presently not available, this compared the ear development of the pig and rabbit embryos, which indicate that the ear of the pig and rabbit develob in the same manner and the rabbit embryos can be used in the future instead of pig embryos for studying ear development.

Intradural communication of L3 and L4 ventral nerve rootlets of spinal nerves.

Normally, the nerve roots within the dural sec never communicate with one another. Even the fusion of the ventral and dorsal nerve roots to form the spinal nerve occurs outside the dural sac. In dissecting the spinal cords of 54 cadavers, we found one abnormal case in which the ventral nerve rootlet of the L3 spinal nerve gave a branch which joined with the L4 nerve rootlet within the dural sac. This communication consisted only of motor fibers. This pattern is different from patterns of distribution of normal spinal nerves, which are described by their segmentation and peripheral distribution patterns, both of which occur outside the dural sac and comprise of both motor and sensory fibers. Several causes for this abnormality have been proposed. Firstly, some neurons of the L4 anterior horn may have interposed with the L3 anterior horn cells. These neurons may have given axons and which joined with the L3 spinal nerve, then split back to join with the L4 spinal nerve, to ultimately supply the myotome of the L4 somite. Secondly, the fusion of myotomes of several somites to form one specific muscle may have developed sooner than its nerve and may have influenced the communication between the L3 and L4 nerve rootlets within the dural sac. An ultrastructural study of the communication segment by TEM clearly reveals a bundle of myelinated nerve fibers which are all peripheral nerves with their Schwann cells covered externally.

Development of the rabbit’s respiratory system.

The human respiratory system begins to form about day 26-27 after fertilization. It is first indicated by a median laryngotracheal groove in the caudal and ventral wall of pharynx. The endoderm which lines the laryngotracheal groove gives rise of the epithelium and glands of the larynx, trachea, bronchi and the pulmonary lining epithelium. The connective tissue, the cartilage and the smooth muscle of these structures develop from the splanchnic mesoderm surrounding the forgut. In studying the development of the respiratory system at the Department of Anatomy, Siriraj Hospital medical students should trace the serial section of 10 mm. pig embryos. In doing this, they will be able to observe the laryngotracheal groove at the floor of the pharynx and when tracing the sections caudally, they will be able to observe the trachea, esophagus and the bifurcation of the trachea forming primary bronchi as well as smaller of branches of present study attempts to show the development of respiratory system of rabbit embryos in order to find the most suitable for use for as a laboratory model for medical students, embryological studies. A 10mm. rabbit embryo can be used instead of a pig embryo for studying the development of the respiratory system, as nowadays pig embryos are not available.

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’s urinary system serial sections study of 12-14 mm rabbit embryos and a 10 mm pig embryo.

The urogenital system develops from the intermediate mesoderm, the coelomic epithelium and the endoderm of the urogenital sinus. The urinary system of mammal is characterized by three sets of kindneys, i.e. the nonfunctional pronephros, the mesonephros and the functional metanephros. The metanephros or the permanent kidney develops from the ureteric bud and metanephrogenic tissue. At the beginning the kidney is located in the pelvic region but later gradually ascends to the abdomen. The urinary bladder development of human urinary system in the Department of Anatomy, Siriraj Hospital, we have employed serial sections of 10-15 mm pig embryos as laboratory models. This method of laboratory study is helpful in understanding and recognizing how the kidney forms. It is quite regrettable that nowadays the pig embryos are no longer available. Thus, it is necessary to find another suitable laboratory model and study the details of its normal kidney development. In this study, we demonstrated that 12-14 mm rabbit embryos can be used instead of pig embryos as the development of the metanephros is very similar. Although the rabbit’s mesonephros is smaller than that of the pig, it resembles the human mesonephros more closely. For this reason, the rabbit embryo is suitable for use as a laboratory model for embryology education of urinary system.

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.

Leptospirosis 2001.

A 20-year-old man was admitted to Siriraj Hospital because of high fever and jaundice. He also had acute renal failure. According to the other clinical manifestations and laboratory investigations, the differential diagnosis included severe systemic infections, especially leptospirosis and scrub typhus. A definitive diagnosis was obtained by a positive microscopic agglutination test for Leptospira interrogans, serovar bratislava. Serological tests for scrub typhus and dengue infection were negative. The number of patients with leptospirosis has been increasing in many hospitals and outbreaks of the disease have been reported in northeastern Thailand since 1997. In October 1999, Leptospira interrogans, serovar pyrogenes was isolated from the blood of a febrile patient with clinical leptospirosis in Burium province. This pathogen was used to study the progressive microanatomical changes within organs including the kidney, lungs, liver, gastrocnemius and hamstring muscles of infected hamsters. The kidney showed degenerative changes of the renal tubular cells and many pathological appearances of the glomerular tuft. Interstitial nephritis and pyelonephritis were also found. In the lungs, the alveolar and interalveolar capillaries were engorged with red blood cells. Both bronchopneumonitis and interstitial pneumonitis were observed. The liver showed cloudy swelling of hepatocytes which lead to dissociation of the hepatic cords. Vascular and sinusoical congestion, prominent Kupffer cells and inflammatory cell infiltration in the parenchyma, and sinusoids as well as the portal area were demonstrated. Hepatocellular necrosis was found scattered throughout the hepatic lobules. Some hamsters showed blood vessel congestion in the gastrocnemius and hamstring muscles. Inflammatory cell infiltration was shown in the perimysium of the gastrocnemius muscle of one hamster. Another showed necrosis of some muscle fibers together with inflammatory cell infitration which are sings of muscular inflammation. The prevention and control of Leptospirosis is discussed.