The distribution of the ganglion cells in the chicken retina was observed using the whole mount preparations.

Cell counts of the ganglion cell layer in the chicken were about 4,500,000 and this value was considerably numerous compared with those in mammals. The isodensity lines of the retinal ganglion cells in the chicken had an oval form increasing the density toward the central area and did not formed the visual streak shown in mammals living on the ground. These findings suggest the difference in the extent of the view field associated with the living habits.

The ganglion cells in the retina have been classified in three types; large sized α-, medium sized β- and small sized γ-type cells. And these have been different from each other in the physiological significance. The larger α-type ganglion cells were mainly observed in the peripheral regions differing from the distribution centering the central area in mammals.

There was the first occurrence of IBK in cattle imported from USA to breeding farm of Aomori in 1970. Since then, the occurrences of the disease had been recognized in 16 prefectures of Japan in 1972.

The prevalence of IBK in an area contaminated by the causative agent of the disease was investigated clinically, bacteriologically and pathologically. In some farms of Aomori, M. bovis, the causative agent of IBK, was frequently isolated from the nasal and ocular swabs of cattle suffering from IBK or those from the apparently healthy cattle. Furthermore, it was observed that the disease spread from the farm where the disease was firstly observed by OKA (1970) to the neighbouring farms.

These results indicated that the main route of such endemic outbreak of this disease as mentioned above must be the transportation of cattle with or without symptoms from the original herds contaminated with M. bovis to the other herds. However, the role of insects concerning spread of this disease could not be neglected.

Apparently healthy 523 colony-born cynomolgus monkeys (Macaca fascicularis) aged from 0 day to 19 years were examined for the findings of the ocular fundus by using ophthalmoscope. One drop of the mixed solution of 0.5% tropicamide and 0.5% phenylephrine hydrochloride was instilled into each eye of the animal. Then, those monkeys were anesthetized with ketamin-HCl at the dose level of 10mg/Kg B.W.. Either with or without pre-injection of fluorescein in, photographs were taken with Kowa RC-II ophthalmoscope-camera by using daylight typed color film. The flash intensity for taking regular photographs was set at 50W-2 and fluorescein angiographs were set at 100W of the transformer's position.

Following findings were obtained in each age class. Retinal color was salmon pink with 0 to 3-day-old neonates, salmon pink and blue to green with 3-week to 4-week-old animals, blue to green with 6-week to 1 year old macaques, and brown with 7-year-old monkeys. As regards optic disc, 0- to 3-week-old animals were observed to be light orange in color, and the infants aged more than 4-week showed orange color. Retinal arteries and veins were lightly reddish in the color with every age class. Macular color was salmon pink in 0-day-old cases, slightly dark in 3-day-old neonates and very dark after 3-week of age. Little retinal reflex was noted in 0 and 1-week-old animals. The reflex was observable in 2-week-old animals without fail, attaining the strongest intensity in 1-year-old monkeys and gradually decreasing its intensity in 3- to 19-year-old animals. Central pit's reflex was detectable after 6-month of age. Retinal hemorrhages were recorded about 70% neonates born in natural condition. It was noted that retinal hemorrhages disappeared at 3-day to 2-week of age. Persistent hyaloid artery was observed in all newborn monkeys. It was noted that persistent hyaloid artery was faded out at 3 to 6-week of age.

Ophthalmoscopic and pathologic examinations were carried out on 832 eyes of 416 male and female aging Fischer 344 rats. Various spontaneous ocular lesions were observed in rats of both sexes between 83 and 109 weeks of age by ophthalmoscopic examination. Spontaneous retinal degeneration occurred in 2.4% of male and 2.5% of female rats. The retinal degenerations were characterized by loss of the photoreceptor layer and microcystoid degeneration in the inner nuclear layer. Retinal lesions associated with cataract were examined in comparison with spontaneous retinal degeneration. The loss of the photoreceptor layer, cystoid degeneration, folding, proliferation of the pigment epithelium and gliosis were observed in the retina of rats with cataract. There were also various changes in the sclera and atrophy of the optic nerve.

The number of the photoreceptor cells and thickness of the photoreceptor layer gradually decreased with advance in age. There was a close relation between spontaneously occurring retinal degeneration in Fischer 344 rats and aging of the animals.

The changes with advancing age on retinal blood vessels of ocular fundus were investigated in six steers. The calves of Holstein-Friesian (body weight: 48.2 ± 0.75 kg) were introduced to the Cattle-breeding Center of National Federation of Kaitaku Agricultural Cooperative Associations in Tochigi Prefecture and reared there. Photographs of the fundus were taken at 6th to 277th day after the initial day of introduction with an ophthalmoscope camera (Kowa RC-II) by using of color films (Kodak Ektachrome ASA 200) under the non-anesthetic condition. The results were as follows: The rate of diameter of the superior vein to the long distance of optic disc in both eyes showed a gradual decreasing with advancing age at the points of 1.0, 1.5 and 2.0 R (R=long distance of optic disc) far from center of the disc. The differences between data of 6th and 277th day were significant (p<0.05) at the points of 1.5 and 2.0 R, respectively. There were mostly constant in any stage of age on the angle-values consisted of running line of superior and nasal or temporal arteries, respectively. Little changes with advancing age on A/V ratio of nasal or temporal vessels were recognized at the points of 1.0 and 1.5 R. The persistent hyaloid artery was observed throughout the investigation.

In recent five years, ocular fundus of domestic cats was investigated. The majority of 1098 examined animals harboured in Osaka Prefecture, others were in Saitama and Fukushima Prefecture respectively.

Nearly all animals were Japanese domestic shorthaired and over eighty percent were adult or senile staged. The sexual ratio was 1.5(M): 1.0(F).

The cats were reared in filtrated high clean air supplied cage-system individually located in air conditioned animal facility of the University, and observed their ocular fundus under general anesthetic condition with Ketamin-HCl.

The micropapilla in optic disc zone, general or partial atapetal, lacking of pigmentation in retinal zone were recorded. The retinochoroidal coloboma was observed monolaterally in one case of JDSH. These anomalies were under 1.1 percent as incidence-ratio.

The central retinal degeneration was recorded over six percent of investigated JDSH.

The rate of male cases of this condition was higher than of female significantly (p<0.05). The cases in adult or senile stage were more observed than of juvenile, however, differentiation between above stages on incidence ratio was not significant (p<0.05).