Abstract
A histological study on ovaries from 3 aged cows (cases I, II, and III; 28, 21, and 17 years old, respectively) was carried out, and some histological characteristics which were common to the three cases were found. Because clinical observation had been incomplete on the sexual symptoms of these animals, the significance of these histological findings was not discussed enough. No normal growing follicles nor primordial follicles were found in any ovary. Although several structures having a follicular outline were found in an ovary of the youngest animal of the three, the degeneration of oocytes seemed to be in progress, and the follicle was regarded as atretic. For the above-described reasons, it seems probable that oocytes might have almost disappeared from the ovaries of the cow over 17 years old. Concomitantly with the disappearance of oocytes from the ovary, the organ becomes essentially a solid stromal tissue. Especially, in an ovary of case I, such tendency was so pronounced that the ovarian stroma exhibited a completely fibrotic body. In two cases of the three, a unilateral growth of ovarian cyst was found. The cystic cavity of case I was filled with white jelly-like substance and that of case III with color-less liquid. In this study, no attempt was made to determine whether these cystic contents had a hormonal activity or not. The folliculoid structure was seen bilaterally in all cases. In the three cases of the present study, the size and frequency of folliculoid structure in the ovary seemed to be larger in a more aged cow. The folliculoid structures observed in this study were classified into two types according to the developmental pattern of trabeculae; one type had granulosa-cell tumors and the other contained cystadenoma. In larger granulosa-cell tumors, a number of colloid bodies of various size were found. These bodies were considered to increrse in size by gradual accumulation. From the results of the histochemical methods employed, it was concluded that the colloid body was composed of polysaccharides containing lipoidal substance. Colloid bodies were observed strictly located in the trabecular tissue. Another characteristic pattern, i.e., a rosette-like structure, was found very commonly in both types of folliculoids. In thc present study, it was clarified that many of such rosette-like structures were cross-sections of trabeculae. Accordingly, it seems necessary to distinguish this rosette-like structure from the Call-Exner body which has been observed in a growing follicle. Apart from the above-described pattern, a folliculoid containing true Call-Exner bodies was also found.
