The number and distribution of the retinal ganglion cells in the 2 years old Korean native cattle was determined from whole flat mounted preparation stained with methylene blue and thionin. The total number of retinal ganglion cells was estimated to be 3,085,200 in the bovine retina ranging from 2.214mm** (2) in total area. Visual streak was recognized at the area 2.5mm superior to the optic disc and ganglion cell density drops off rapidly to the direction superior to and inferior to the visual streak. Area centralis (6,800 cells/mm** (2)) was located at the area 10mm temporally from the point of 3mm superior to the optic disc. The number of alpha-type ganglion cells (above 15 micro) was 57,000 in the bovine retina and alpha-type ganglion cells constituted 18.5 % of the total cells. The relative frequency of alpha-type ganglion cells was higher in the peripheral regions than in the visual streak, especially higher in the superior-temporal quadrant than in other region of the bovine retina.

This paper dealt wih the distribution of Shigella spp. on 5 piggeries in Taegu and Kyongbuk during the period from August to October 1987. Isolated Shigella were examined for serogrouping, antimicrobial drug resistance and detection of R plasmid. Genetic properties of R plasmid in Shigella were examined for fertility inhibition (F1) and gel electrophoresis was performed for the isolation of plasmid DNA. Of total 2,978 samples from 5 piggeries, 82 strains (2.8 %) of Shigella spp. were isolated from 82 samples. The isolated strains were identified as S. dysenteriae (60 strains), S. flexneri (20 strains) and S. sonnei (2 strains). Of the 82 strains examined 67 (95.1 %) were resistant to one or more antibiotics, such as ampicillin (Am), chloramphenicol (Cm), kanamycin (Km), nalidixic acid (Na), rifampicin (Rf), streptomycin (Sm), sulfademethoxine (Su), and tetracycline (Tc) and higher resistance to Su (90.2 %), Sm (63.4 %) and Tc (63.4 %). Of the 78 resistant Shigella strains 26 (33.3 %) harbored conjugative R plasmids and the transfer frequency of Sm (50.0 %), Cm (33.3 %) resistance was much higher than that of the other drug resistance. The most common resistant patterns were SmSuTc, Su and AmSmSuTc. Out of the 26 Shigella R plasmids examined for Fi, 14 (53.8 % were Fi + and the remainder were Fi-. The plasmid DNA profiles in Shigella spp. (9 strains) isolated from pigs were confirmed as being 2 to 9 fragments by the gel electrophoresis. Their molecular size ranged 2.17 to 87.62 kilobase (Kb). All strains of Shigella spp. consisted in 15.4 Kb plasmids.

In order to investigate the morphological characteristics of epididymal duct of the squirrel, the histological and histochemical studies were carried out. The epididymal duct can be divided into 9 segments by histological and histochemical features. Segments 1 to 5 were located in the head, segments 6 and 7 in the body, and segments 8 and 9 in the tail of the epididymis. The apical cells were numerous in the segment. Clear cells which has a compact, deeply staining nucleus and a characteristically clear cytoplasm were scattered in the epithelium throughout the duct. Interepithelial clear cells which had PAS-positive granules tended to increase in number caudally. Strong PAS-positive reaction was detected at the intralumen of the segments 3, 8 and 9. Acid phosphatase activity was relatively high in the basal cytoplasm of the segment 7, and then in the supranuclear region of the segments 8 and 9. Alkaline phosphatase activity was weakly positive or negative except the segments 3 and 4. ATPase activity was strong in the free surface of the epithelium in the head and the entire cytoplasm in the body and tail, and SDH activity was generally weak except for the body where it was more intense.

Effect of raising types and environmental conditions on the infection of Toxoplasma in the swine, the cat and the man were studied in Cheju Island from Sept. 1987 to Aug. 1988. Blood samples were taken from 214 conventionally raised swine in 6 villages and 506 swine raised in swine specialized farms, 122 cats raised under free moving or restrained conditions in 8 locations, 113 butchers, and 210 villagers. Toxoplasma antibody values of the blood sera were determined using the enzymelinked immunosorbent assay (ELISA). The eating type of viscera was also investigated by using questionnaires. When ELISA method was used, the percentage of Toxoplasma infect swine among the conventionally raised and of those raised in swine specialized farms were 60.7 % and 21.3 %, respectively. The respective antibody values (+- SD) were 0.589 (+- 0.310) and 0.385 (+- 0.237) and differed very significantly (p<0.01). A significant difference was also found in antibody values among 6 villages (p<0.05). The mean infection percentage of Toxoplasma in the cat was 38.2 %, the infection percentage for cats raised under free-moving and restrained condition were 37.0 % and 38.2 % respectively. The respective antibody values (+- SD) for Toxoplasma were 0.600 (+- 0.614) and 0.637 (0.645), and did not differ significantly. The infection percentage of Toxoplasma in villagers and butchers were 26.2 and 38.3 % respectively. The respective antibody values (SD) for toxoplasma were 0.429 (+- 0.195) and 0.341 (+- 0.236), and differed very significantly (p<0.01). There were also highly significant differences Pyo-sun and other village (p<0.01). Analysis of the questionnaires showed that 26.0 % of 392 villages ate liver and some villagers ate other viscera.

The present study was conducted to investigate the Bordetella bronchiseptica infection in Youngnam swine herds during the period of August 1986 to July 1987 and some properties of the organisms isolated from these Korean swine. B. bronchiseptica was recovered from 25 of 70 (35.7%) growing pigs of 4 to 10 weeks of age and from 12 of 13 (92.3%) herds. From 115 slaughter pigs, 58(50.4%) pigs were culture positive and the pigs from 13 of 14 (92.9%) herds were found to be infected with B. bronchiseptica. The majority of biochemical and cultural properties of B. bronchiseptica isolated from Korean swine were identical to those of the standard strain employed and some 97.6% of the isolates showed the characters of phase I organism on primary isolation.

The first outbreak of aujeszky's disease (AD) was identified from piggery located at the southern part of Korea in July, 1987. This piggery suffered from a significant economic loss caused by unexpected piglet mortality and reproductive failure. Etiologic viral agents were isolated from tonsil and spleen of the infected piglets, and the isolates produced a typical cytopathic effect of herpesvirus with giant cell formation when inoculated in many different cells. Subsequently the field isolates were characterized as suid herpesvirus I by cross-neutralization test and indirect fluorescence assay utilizing specific monoclonal antibody, and proved to be a pathogenic strain of AD virus(ADV).

Mating experiments were performed to elucidate the distribution of perfect state of Microsporum gypseum complex originating from animals and soils in Korea. A total of 30 strains of M. gypseum complex, composed of 16 from animals and 14 from soils, mated with the tester strains of Nannizzia incurvata, N. gypsea and N. fulva. Among 30 strains of M. gypseum complex examined, 16 strains (53.3%) were N. incurvata, 13 strains (43.3%) N. gypsea and 1 strain (3.3%) N. fulva. Among 13 strains of dog isolates, 8 strains (61.5%) were N. incurvata and 5 strains (38.5%) N. gypsea. And each strain isolated from Korean native goat, monkey and albino rat was N. gypsea. Among 14 strains of soil isolates, 8 strains (57.2%) were N. incurvata, 5 strains (35.7%) N. gypsea and 1 strain (7.2%) N. fulva. And - mating type was more frequently obseved than + mating type in the strains of N. incurvata and N. gypsea. By this study, N. fulva was isolated the first time in Korea.

The changes of acid-base status in vitro of the venous blood for 24 hrs in ten Korean native goats were investigated. The acid-base parameters were measured within ten minutes after collection of the blood, and every hour during the first six hours and finally after twenty-four hours of storage. Blood samples were stored at two different temperatures (0-4 deg C and 21-24 deg C). Twelve goats were induced acute acid-base disturbances by intravenous infusion of either hydrochloric acid or sodium bicarbonate and inhalated with CO2 gas mixture (20% C02, 80% O2) or hyperventilation were performed by means of respirator.