This experiment was carried out to establish the immunohistochemical diagnostic method for infectious pancreatic necrosis in the monolayers of CHSE-214 cell cultures and paraffin-embedded tissue sections from rainbow trout infected with infectious pancreatic necrosis virus(IPNV). Specific identification of IPNV antigens was often demonstrated in the pancreatic exocrine cells, and less in the intestinal mucous epithelia and the renal hemopoietic tissues by the use of monoclonal antibodies against capsid protein VP2. The specific reaction was seen as a distinct red cytoplasmic color, often as small granules of various sizes. The result showed that streptavidin alkaline phosphatase immunohistochemisry specifically identified IPNV antigens in both infected cell cultures and tissue sections.

We investigated the effect of a single intravenous dose of Fumonisin $B_1(FB_1$) of rat kidney on the time sequence. Male Sprague-Dawley rats were intravenouslyin jected with FB$_1$at 1.25 mg/kg and were euthanized at 12 hrs, 1, 2, 4, and 6 days after the injection. In $FB_1$ treated rats, serum BUN and creatinine were elevated from 12 hrs. Microscopically, the initial target site was tubules of inner stripe, with mild degenerative and necrotic changes at 12 hrs, but the tubules recovered on day 4. In outer stripe, there were only a few scattered necrotic cells on day 1. These changes became more obvious over the time passed and most severe on day 4. On day 6, regeneration occurred, manifest as hypertrophic, basophilic tubular cells. The dying cells were proved to necrotic cells instead of apoptotic cells by TUNEL. Ultrastructural changes were cytoplasmic vacuole, dilated endoplasmic reticulum, swollen mitochondria, ballooned microvilli of the tubular cell in the outer stripe. These results showed that the renal tubules of outer medulla were the target to $FB_1$-induced nephrotoxicity in the rat. However, initial target was mner stnpe of medulla.

To elucidate the mechanism of age-related development in FGS/NgaKIST mice with spontaneous glomerulosclerotic lesion, we examined expression and localization of various cytokine mRNA in the kidney in the progression of diseases. This mouse model is the first to develop spontanously occuring glomerosclerotic lesion in the kidney. In this study, we detected the up-regulation of local cytokine genes such as IL-1$\beta$, IL-2, IL-6, IL-10, TNF-$\alpha$, TGF-$\beta$, and IFN- $\gamma$ in the kidneys. In RT-PCR and Southern blot analysis, we detected gradual expressions of cytokine mRNA of IL-1$\beta$, IL-2, IL-6, IFN- $\gamma$, and TNF $\alpha$ mRNA during the course of disease. Other cytokines including IL -10 and TGF -$\beta$ were found to be appeared the slightly expressed level at 3 to 12 weeks before onset of inflammatory lesion but they are highly expressed at the end-stage of the disease accompaning high proteinurea and wasting. In situ RT-PCR, each cytokine mRNA were specifically localized in a variety of cells including mesangial, endothelial, parietal epithelial, tubular epithelial, arterial muscle cell, and infiltrated inflammatory cells. In addition, TNF - $\alpha$was detected moderately in the visceral and parietal epithelial cell, but weakly in endothelial and mesangial cells, whereas IL-1 $\beta$ and IL -6 were strong in mesangial regions. IL-6 and TNF- $\alpha$ was highly localized in the damaged proximal and collecting tubules. Especially, TGF -$\beta$ mRNA was highly found in mesangial cells within glomerulus and interstitium during the end-stage of this disease.. These results indicate that pro inflammatory cytokines such as IL-1 $\beta$, IL-2, IL-6, and TNF- $\alpha$ were gradually expressed from the early stage of this disease to the end-stage, and that IL-10 and TGF-$\beta$ may be important in the accumulation of extracellular matrix(ECM) within glomerulus and periglomerular fibrosis in the progression of this disease as well as tissue destruction in end-stage of this disease.

Phosphamidon(PMD) is orgnophosphate insecticide broadly using in agriculture. In order to study PMD toxicity in the testis, histopathological change and apoptosis were assessed following acute and chronic oral administration in rats and chickens. In acute studies, histopathological changes included necrosis and desquamation of spermatogenic cells, multinucleated giant cells in the lumen of seminiferous tubules, and necrotic cells and the giant cells in the epididymal lumen. Atrophy of seminiferous tubule was seen in the chronic exposure with low doses. The toxic effects of PMD in chronic exposure including clinical signs and histopathological changes were more pronounced in chickens than rats. Apoptosis assessment was performed by TUNEL method and Hoechst staining. TUNEL-positive apoptotic cells were found in spermatocytes of seminiferous tubules, testicular apoptosis was more prominent following acute exposure than control and chronic exposure. Above mentioned result noticed that PMD causes apoptotic death and effects directly the spermatocytogenesis.

The morphologic changes of small intestinal epithelium in pigs diagnosed as porcine epidemic diarrhea(PED} by virus isolation and immunohistochemistry were studied through light microscope and transmissible electron microscope. On semi-thin section, the histologic findings showed severe villous atrophy and fusion with hyperplasia of cuboidal epithelium in the villi, inflammatory cell infiltration in lamina propria, and increased mitotic figures in the crypt. The structural changes were mostly restricted to the cytoplasm of affected absorptive epithelium of villi. 3 types of epithelial changes were found; degenerated virus-affected cells, undifferentiated cuboidal cells, and normal columnar cells. On electron microscopy, round to spherical viral particles of 50∼l00nm in diameter were found within the dilated vesicles and endoplasmic reticulums of degenerated cells, which had decreased their cytoplasmic electron density due to dilated and missing organelles(e.g. mitochondria, ERs, etc.). Microvilli were shortened and sparse, leaving denuded terminal web of the villous epithelial cells. Fat globules were often found within slightly degenerated enterocytes. On the tip of villi, severely damaged cells were exfoliated and replaced by undifferentiated cuboidal cells We found distinct ultrastructural changes in the jejunal epithelium confirming PED virus infection is involved in malabsorptive diarrhea.

Canine dermatosis associated with zinc deficiency naturally occurred in three districts of Kyungpook. A diagnosis was made by clinical findings, clinico-pathological examinations, skin biopsy, and therapeutic tests. The result was diagnosed as a zinc-deficient dermatosis. The disease occurred in rapidly growing Tosa-dog hybrids 5 to 7 months old. Skin lesions included erytherma, alopecia, crusting, scaling around the mouth, eyes, legs and tail. Clinico-pathological findings were decreased serum zinc levels, slightly increased white blood cells, and secondary Staphylococcus intermedius infection of the crusts. The skin biopsies for histopathological examination revealed marked parakeratotic hyperkeratosis. The patients with skin lesions were successfully treated by zinc methonine(Zinpro) medication In conclusion, serum zinc level and skin biopsy are very helpful in diagnosis of canine zinc-deficient dermatosis.

A case of avian tuberculosis is reported in a 10-year-old female Mandarin duck (Aix galericulata). Numerous multi focal to coalescing, caseo-necrotic granulomas in variable sizes were scattered throughout the major parenchymal organs. Histologically, the granulomas have caseonecrotic and occasionally mineralized centers that are surrounded by macrophages, epithelioid cells and Langerhan's type multinucleated giant cells and then by lymphocytes and a few plasma cells and fibrosis. Ziehl - Neelsen's stain revealed myriads of acid-fast bacterial rods present in the cytoplasms of macrophages and multinucleated giant cells.

Metastatic squamous cell carcinoma was described in two female Pere David's deer reared at Everland zoo. Both deer with chronic emaciation had the mass on right maxilla(9$\times$11$\times$15cm or 20$\times$17cm) which was composed of miliary tan creamy contents and encapsulated by connective tissue. The undulating contents in the mass was a1so extended in the underlying or adjacent soft palate, maxillary and frontal sinus causing severe bone destruction. In one deer, two fistula were also noted in the right periocular area. Histologically, the neoplastic masses of both deer consist of anastomosing cords or nests of squamous epithelial cells with intercellular bridge or keratin pearl formation. The neoplastic cells invade deep into the subcutis and bony tissue. Mitotic figure was rare. Multifocal areas of necrosis and hemorrhages were also noted in the dermis. Metastasis to maxilla and ethmoid bones and/or to submandibular lymph node was noted in both cases. The diagnosis was based on the results of histopathology.

A dead marten(Martes melampus) showing cough, ataxia and convulsion of hind limb followed by seizures, was submitted for diagnosis to the Pathology Division of the National Veterinary Research and Quarantine Service. In the gross lesions, lung was congested and consolidated and meningeal blood vessels were mildly congested. Histopathologic findings were diffuse interstitial pneumonia and nonsuppurative meningoencephalitis with malacia of cerebral and cerebellar white matter. Eosinophilic inclusion bodies were observed in neurons and astrocytes and oligodendroglial cells of brain and transitional epithelium of kidney. Using FA test and PCR method, specific antigens of canine distemper virus were demonstrated in the brain.

Clinically, three holstein dairy cattle showed the inappetence and decrease of milk production with severe lameness and pain. Grossly, strawberry-like proliferation of the skin between the heel bulbs were observed 4${\times}$5${\times}$1.5cm in size. Histopathologically, severe hyperplasia of epidermis, parakeratotic hyperkeratosis and multifocal ulceration of cornified cell layer, acanthosis, spongiosis of prickle cell layer and irregular arrangement of basal cell layer were seen. And focally observed the lesions of necrotic vasculitis, infiltration of inflammatory cells, congestion and hemorrhage. Spirochete bacteria were found in necrotic and outer proliferated epidermal cells by Levaditi's silver stain. Clinical and pathological findings were consistent with dermatitis verrucosa.