BUFFALO FETAL COTYLEDONS CONTAIN CERTAIN FACTORS THAT SUPPRESS COMPENSATORY OVARIAN HYPERTROPHY IN MICE

We examined the compensatory ovarian hypertrophy (COH)-suppressing activity in 20% ammonium sulphate precipitates from 0.9% saline extracts of fetal cotyledons and maternal caruncles collected between 45 and 112 days of gestation. These extracts were injected into mice on the morning of dioestrus after removing their left ovaries, while the control mice received buffalo serum protein. Seventy-two hours later, mice were killed and the right ovaries were weighed. The degree of COH was expressed as the percentage increase in the weight of the right ovary to that of the left. COH suppressing activity could be extracted from fetal cotyledons but not from maternal caruncles. The inhibitory factor is heat-labile, inactivated by trypsin digestion and is not extractable by either charcoal or ether. It eluted as two distinct peaks from Sephadex G-100 columns. Both protein peaks from fetal cotyledonary extracts caused suppression of COH. This inhibitory substance(s) may play a role in regulation of follicular dynamics during early pregnancy. © 1990.