This investigation was carried out to study morphological and chronological aspects of the development of the Harderian gland in the Mongolian gerbil(Meriones unguiculatus). Male and female Mongolian gerbils were sacrificed on days 1, 3, 5, 10, 30 and 60 after birth and their Harderian glands were processed for light microscopic observation. The result obtained were summarized as follows; 1. In 1-day-old Mongolian gerbil, Harderian gland was well distinguished from other tissue structures. It was composed of several immature tubules, and these tubules were separated each other by undifferentiated mesenchymal connective tissues. 2. In 3-day and 5-day-old Mongolian gerbils, the arrangement of tubules in the gland was more condensed than that of 1-day-old Mongolian gerbil. The excretory ducts started to appear in the connective tissues located between lobes. 3. In-10-day-old Mongolian gerbil, small lipid vacuoles began to be found in the cytoplasm of the secretory cells of the Harderian gland. There were some mucus-secreting cells within the epithelium of the excretory duct found in the interlobar connective tissues. 4. In 30-day-old Mongolian gerbil, there was markdely increased number of the tubules in the glands. The epithelial cells of the tubules were typically columnar in shape. Most of the columnar epithelial cells contained many small lipid vacuoles, although a few cells contained large lipid vacuoles. 5. In 60-day-old Mongolian gerbil, the Harderian gland exhibited the typical structural characteristicsl of the adult gland. The mature glandular structrues were more distinct than those of 30-day-old animals.

Ischemic damage in the selectively vulnerable populations of neurons is thought to be caused by an abnormal accumulation of intracellular calcium. It has been reported that the neurons, expressing specific calcium binding proteins, might effectively control intracellular calcium concentrations because of a high capacity to buffer intracellular calcium in the brain ischemic condition. It is uncertain that parvalbumin, one of the calcium binding proteins, can protect the neurons from the cerebral ischemic damage. Recently, treatment of kappa opioid agonists increased survival rate, improved neurological function, and decreased tissue damage under the cerebral ischemic condition. Many evidences indicate that these therapeutic effects might result from regulation of calcium concentration. This study was desighed to analyze the changes of number in parvalbumin-positive neurons after cerebral ischemic damage according to timepoints agter cerebral ischemic inductionl In addition, we evaluated the effect of GR89696 (kappa opioid agonist) or naltrexone(non selective opioid antagonist) on the changes of number in parvalbumin expressing neurons under ischemic condition. Cerebral ischemia was induced by occluding the common carotid artery of experimental animals. The hippocampal areas were morphometrically analyzed at different time point after ischemic induction(1, 3, 5 days) by using immuno-histochemical technique and imaging analysis system. The number of parvalbumin-positive neurons in hippocampus was sighificantly reduced at 1 day after ischemia(p0.05). Furthermore, the number of parvalbumin-immunoreactive neurons was dramatically reduced at 3 and 5 days after cerebral ischemic induction(p0.05) as compared to 1 day group after ischemia, as well as sham control group. Sighificant reduction of parvalbumin positive neurons in CA1 region of hippocampus was observed at 1 day after cerebral ischemic induction. However, sighificant loss of MAP2 immunoreactivity was observed at 3 day after cerebral ischemia. The loss of parvalbumin-positive neurons and MAP2 immunoreactivity in CA1 region was prevented by pre-administration of GR89696 compared to that of saline-treated ischemic group. Furthermore, protective effect of GR89696 partially reversed by pre[treatment of naltrexone. These data indicate that parvalbumin-positive neurons more sensitively responded to cerebral ischemic damage than MAP2 protein. Moreover, this loss of parvalbumin-positive neurons was effectively prevented by the pretreatment of kappa opioid agonist. It was also suggested that the changes of number in parvalbumin-positive neurons could be used as the specific marker to analyze the degree of ischemic neuronal damage.

A nation wide sero-epidemiological survery of porcine reproductive and respiratory syndrome(PRRS) was carried out to analyze the current status of the PRRS virus infections in the field using the indirectr immunofluorescent antibody assay(IFA) with the field isolate PL96-1. Since the first report of the antibody detection to PRRSV in 1993, the prevalence of seropositive pigs has increased dramatically and the data indicate that over 21% of the pigs and around 60% of the farms showed seropositives to the PRRS virus. A slightly higher positive rate was recognized in breeders than fattenings and it might be due to the higher age at the time of testings. No significant regionl defferences were detected in the sero-epidemiological survey. Higher sero-positive rate in growers indicatesthat PRRSV infection in the field was common after weaning(around 40 days). However, the number of seropositive pigs were declined in fattening pigs. Sows showed around 26% of sero-positive rate that there is a higher chance of continuous virus circulation in the infected farms. Low rate of sero-positivity in boars(9.8%) implies that there is high demand in proper controlmeasures to prevent virus spreading through breeding procedures such as natural or artificial insemination Therefore it was concluded that PRRSV infection in domestic swine herds is endemic and the positive rate and economic loses will be increased by spontaeous infections in naive farms.

In the mannalian ovary, follicular development and stresia continuously occur during the reproductive cycles. Follicular atresia occurs through granulosa cell apoptosis. Apoptosis is known as the physiological cell death, which is regulated by bcl-2 gene family. In the vcl-2 gene family, bcl-2 and bcl-xLong are known as inhibitors of apoptosis, whereas bax and bcl-xShort are known as inducer of apoptosis. We thought that bcl-2 protein is associated with follicular development and atresia. But it is not known that the distribution of cells containing bcl-2 protein during follicular development and atresia. Therefore, to examine the distribution of cells with bcl-2 protein during ovarian follicular development and atresia. Therefore, to examine the distribution of cells with bcl-2 protein during ovarian follicular development and atresia, the immunohistochemistry was used ih the rat ovary. Bcl-2 immunorectivity was localized in the intestitial cells, theca externa cells and granulosa cells around of antrum. All positive sighals were observed in the cytoplasm of these cells. Positive sighals were strongly observed in the interstitial and theca externa cells of growing antral follicles. While, positive signals were weakly observed in these cells from atretic antral follicles. Positive sighals were very weakly observed in the granulosa cells of growing and atreticantral follicles. According to these data, we suggested that bcl-2 proteins which were wtrongly expressed in the interstitial cells and theca externa cells of growing antral folicles inhibit follicular atresia. And wer purposed that bcl-2 proteins regulated follicular development and atresia through the action of acl-2 gene family.

The regional distributions and relative frequencies of the gastrin, secretin and pancreatic polypeptide(PP)-immunoreactive cells in the gastrointestinal tract of the fetus(180 days of gestation) of Korean native goat were sutdied with immunohistochemical(ABC) methods. Gastrin-immunoreactive cells were detected in fundus, pylorus and duodenum and these cells were most predominant in pylorus. Secretin-immunoreactive cells were observed in pylorus, duodenum and ileum. PP-immunoreactive cells were restricted to fundus. These immunoreactive cells were situated in surfact epithelium and mucosal gland regions. The regional distribution and relative frequency of PP-immunoreactive cells was somewhat different to the adult Korean native goat. Immunoreactive cells in thesurface epithelial regions were open typed cells which were spindle shaped cells but closed typed cells which were round or/to spherical shaped cells were observed in the mucosal gland regions.