The physiological uterine secretion of rats and its activity in dispersing ovum cumulus cells in vitro.

The quantity of physiological uterine fluid secreted by rats exhibiting a regular four-day sexual cycle was measured at every stage and the freshly ovulated rat ova, surrounded by their cumulus cells, were incubated at 37 degrees C in this secretion sample. The results showed that the fluid began to be secreted on the morning of vaginal pro-oestrus and increased steadily for about 24 h. Two declines in quantity are observed, a slight one at the end of pro-oestrus and a marked one about 4 hours after the start of vaginal oestrus which coincided with ovulation. No secretion is obtained either at metaoestrus or at dioestrus. Only the secretion at the oestrus stages caused total dispersion of the corona cells in vitro. This property is retained after freezing, heating to 60 degrees C and lyophilization. A correlation with plasma sexual hormone measurement and some fertility factor contained in uterine secretion was discussed in relation to this dispersing activity.