Chickens at 3-weeks of age were inoculated with a highly virulent strain (SH/92) of Infectious Bursal Disease Virus(IBDV) through ocular and cloacal routes. The infected chickens were killed at 6, 12, 24, 48, 72, and 96 hrs post inoculation (PI) and Bursa of Fabricius(BF) were collected. The sizes of bursal follicules in infected chickens decreased at 48 to 96 hrs PI. Histologically the cellular changes were first evident at 12 hrs PI and characterized by condensation of nuclear chromatin of bursal lymphocytes indicating apoptosis. By 24 hrs PI apoptotic lymphocytes dramatically increased. In addition infiltration of heterophils were also seen in the follicles and in the interfollicular connective tissues. At 48 hrs PI, cystic cavities were observed in the follicles. As the infection advanced the bursal follicles showed atrophy accompanied by disappearance of heterophils and reduction in number of lymphocytes in the cystic cavities which was replaced by proteineous materials. The nuclei of most affected lymphocyte stained positively with the in situ end labeling for apoptosis. Electron microscopy showed viral particles with crystalline array in the lymphocytes of BF infected with IBOV. These results indicated that SH/92 IBDV infection in chickens caused increased apoptosis in the BF.

Apodemus agrarius Pallas has been known to be a reservoir of hanta virus. But there was no report of immune organs. So this study was performed to clarify the relation between Structure and function of immune organ. In the present investigation an immunocytochemistry procedure was used to examine the distribution of T and B cell and macrophage populations in the thymus spleen and lymph nodes. Most of lymphoid organ showed decreased pattern of Ly1 positive T and IgM positive B cells. Macrophage positive cells were deceased in vivo. The present study gives an overview on the immune organ structure and function of Apodemus agrarius Pallas.

This is the first report of c-Jun protein expression and mRNA in a pancreatic islet in a nonobese diabetic(NOD) state mice. In this experiment NOD mice with insulin-dependent diabetes mellitus type I at age 16 weeks(n=7) just before death(n=4) were used. The control group consist of prediabetic NOD(8 weeks n=7) and ICR(8 weeks n=7 and 16 weeks n=7) mice. c-Jun positive cells in the pancreatic islet of NOD mice were localized in the same positions as a-glucagon producing cells. immunoreactivity was negative in the prediabetic NOD(8 weeks) and ICR(8 weeks and 16 weeks) mice. The number of c-Jun positive cells in mice with severe diabetic state just before death were significantly decreased when compared to NOD(16 weeks) mice. Expression of c-Jun in mRNA level was assessed by RT-PCR method. The levels of mRNA in NOD(16 weeks) mice group were elevated in total pancreatic tissues. The present results suggest that the induction of proto-oncogene protein may be of significance in assessing cell specific injury and may play a functional role between pancretic islet $\alpha$-cells and $\beta$-cells in the diabetic state.

An in vivo model for human melanoma was established with the growth and metastasis of SK-MEL-2 cells. The tumor was introduced into C.B-17 SCID(severe combined immunodeficiency) mice intraperiotneally subcutaeously and intravenous inoculations. Tumors developed in 100% of mice inoculated subcutaneously and intraeritoneally both at site of inoculation and as metastatic tumor in the liver lungs and diaphragm. With intravenous inoculation 50% of mice showed metastasis in the spleen. Additionally metastatic foci that were not detected either by gross and/or standard histopathologic examination were demonstrated in the spleen and lungs by immunohistochemistry with HMB-45 monoclonal antibody. We conclude that the SCID mouse supports growth and metastasis of human malignant melanoma SK-MEL-2 cells.

The Opuntia ficus-indica extract(OFE) has been claimed to have several therapeutic properties including anti-inflammation and anti-rheumatoid arthritis in oriental medicine but little is known about their effect on macrophages. This study demonstrated that OFE could stimulate TNF-alpha production in cultured macrophages. which is one of important mediators in autoimmune diseases including experimental autoimmune encephalomyelitis(EAE). In vivo study showed that oral administration of OFE exacerbate the onset of clinical paralysis. This finding suggests that OFE stimulates cytokine production and exacerbates autoimmune inflammatory diseases including EAE.

It has been known that $\gamma$-irradiation usually induces cell death in regenerating stem cell in normal tissues like skin, intestine and hematopoietic organ. The experiment were carried out to evaluate the early response of radiation injury in radiosensitive and intermediate radiosensitive tissues in feeding and starving rats with the doses of 3.5 and 7.0 Gy. The results of the study showed that the histological phenomenon was apoptosis in the doses of the radiation as the early response of tissue injury. Apoptosis were showed organ-specific and cellular specific responses suggesting that the selection of apoptosis be exactly focused on highly renewal organs and cells. It was interesting that the rats starved for 72 hours prior to irradiation induced less apoptosis in liver than fed rats. As for cellular responses it appeared that apoptotic cells were mostly distributed in ductal or periportal cells in liver of feeding rats unlikely in liver of Starving rots which showed no difference in zonal distribution. In salivary gland apoptotic cells in fed rats were highly induced in intercalating and ductal cell population than in acinar cell population although unlikely in starved rats. This study showed the value of apoptosis using the detection system of TUNEL for evaluating cellular damage after radiation injury and the diminished effect of starvation on cell damage after ionizing irradiation.

The incidence of spontaneous testicular atrophy and its morphological changes during stage-specific spermatogenesis were investigated in male Sprague-Dawley rats at 10, 19, and 32 weeks of age. The incidence of testicular atrophy was 0.2%(2/90) 7.9%(9/114) and 10%(4/40) in 4, 13 and 26 weeks respectively. The epididymis with testicular atrophy had low sperm density. In the minimally affected tests scattered tubules showed complete depletion of germ cells without stage specificity. Testes with moderate to severe testicular atrophy showed seminiferous tubules lined with dense Sertoli cell population. While Leydig cells in the interstitium appeared hypertrophy they were immunohistochemically negative for proliferating cell nuclear antigen a marker of cell proliferation.

A fourteen-month-old Holstein bull from a private cattle fattening farm at Ansung county in Kyunggi Province Korea was submitted on August 2nd 1997, for examination at the Pathology Division of the National Veterinary Research Institute. The bull died within 24 hours after developing clinical signs of abrupt inertia, complete anorexia high fever(40.3℃) diffuse severe emphysematous swelling of upper part of the right hind leg lateral recumbancy and paralysis. At necropsy diffuse severe subcutaneous redness and influx of serosanguinous exudate containing gas bubbles had accumulated under the thorax right hip and upper region of right hind leg. Muscles in upper right hind leg were blackish to dark red and yellowish brown in color. Muscle bundles were dry and separated by gas bubbles and serosanguinous fluids and muscles sections from affected regions floated in water. Histopathologically muscle fibers were partially or entirely degenerated fragmented and separated by exudate and gaseous substance mixed with polymorphonuclear cells. Blood vascular walls in affected regions showed severe acute fibrinoid necrosis. Typical large rod-shaped bacteria with or without oval central to subterminal spores were frequently observed in tissue sections stained with H-E and Gram stain. The large Gram-positive anaerobic endospore-producing rods were isolated from the suspension of muscle lesions. Isolated bacteria were identified as Clostridium(CL) chauvoei and CL. sordellii by biochemical tests. This case was diagnosed as blackleg based on the typical clinical signs gross finding histopathological observation and bacteriological results. This is the first case report on blackleg associated with Cl. chauvoei and Cl. sordellii in Holstein cattle in Korea.