A new sudden death in rabbits appeared in China and Korea in 1984 and 1985, respectively, and was recognized to be an acute infectious disease caused by a virus. The disease was reported as a "new viral disease", and thereafter, a tentative name of "viral hemorrhagic disease", "hemorrhagic pneumonia" or "viral hemorrhagic pneumonia" has been described in the case reports. But authors had called the viral disease "rabbit viral hepatitis" due to picornavirus infection, because the principal lesion of the disease was an acute hepatitis. The purpose of this report is to describe the electron microscopic findings on the livers in experimentally infected rabbits. All the livers of the affected rabbits were shown to have degenerative changes of a type that is characteristic of acute hepatitis. In the liver cells, there were dilation of rER and mitochondria, vacuole formation of various sizes, and appearances of many virus-like particles in the vicinity of rER, granular bodies and crystalline arrays of viral particles in the cytoplasm with necrotic changes of the nucleus. Clusters of virus-like particles and viral crystals appeared in the cytoplasm of sinusoid endothelial cells and Kupffer's cells with morphological changes of organelles. Also viral crystals were demonstrated in the cytoplasm of macrophages among the liver cells. On the whole, the liver cells had many virus-like particles and a few crystalline arrays of viral particles. Therefore, this implies that the liver cells are the main site of the viral replication in inducing the viremia. It was concluded that the liver was the primary target organ of this viral disease, and the pathological and the ultrastructural evidence suggest that the virus may belong to genus enterovirus

The present study was carried out to investigate the effects of nitrate (KNO3) on the thyroid glands in rabbits which were administrated KNO3 of 1g/kg/day for 6 weeks. Growth rate, and serum levels for T4, T3 and TSH were observed every week. The histological changes and the weights of the thyroid glands were observed in 6 weeks. The mean growth rates of experiments were decreased significantly in the 1st week, but were increased a little from the 5th to 6th week compared with those of controls. The serum levels for T4 of the experimental group manifested significantly decreased values than those of control through the experimental term consistently and the serum levels for T3 were greatly decreased in the 3rd and 4th weeks. TSH contents of the serum were not changed through the experimental term. The mean weight of the thyroid gland in the experiment was decreased significantly after 6 weeks compared with that of cotrol. In the experimental group, the color of colloid in the thyroid follicles revealed deeper eosinophilic and the heights of the follicular epithelial cells were taller than those of controls. The colloid in the thyroid follicles revealed depletion. As summarized above, the observations suggest that nitrate can be an antithyroid substance in rabbits and it leads the thyroid glands to hypofunctional state

In order to observe the pathological changes of kidney in rabbits infected with the viral haemorrhagic disease, the kidney tissues from the 91 rabbits infected with the viral haemorrhagic disease were examined by light and electron microscopy. On light microscopic observation, the kidney lesions were identified as haemorrhagic glomerular necrosis (33.0 %), membranous glomerulonephritis (20.9 %), thrombotic glomerulopathy (19.8 %) membranoproliferative glomerulonephritis (8.8 %), mesangial proliferative glomerulonephritis (8.8 %) ischemic acute tubular necrosis (7.7 %), and acute serous glomerulitis (6.6 %). On electron microscopic observation, cytoplasmic degeneration of mesangial cells, and irregular thickening of basement membranes with electron dense granular materials were observed. In podocytes swelling of mitochondria, dilatation of endoplasmic reticulum and extensive fusion of foot processes were also observed. Nonenveloped round icosahedral picornaviral particles with a diameter of 28-33nm were detected in the cytoplasm of degenerative endothelial cells, polymorphonuclear leucocytes, and monocytes

This study was carried out to evaluate the possibility of sex preselection by gradients methods using bovine serum albumin in rabbits. Artifical insemination was performed with sperm from the top and bottom layer of rabbit semen separated by bovine serum albumin gradients. Various characteristics of separated sperm, and the conception rate secondary sex ratio at artificial insemination with separated sperm were compared. The sperm from the bottom layer showed significantly high value in motility, percent of normal sperm and progressive motility as compared with control sperm and the sperm from the top layer. The conception rate of sperm from the bottom layer was higher than that of the top layer. But secondary sex ratio was not altered by this methods