Effect of oestrogen and progesterone on the dilatability of the ovine vagina

Abstract

Twenty ovariectoinized ewes were given a single injection of stilboestrol or stilboestrol dipropionate. In ewes given stilboestrol, the rate of increase in apparent vaginal volume and the time required for return to basal levels were similar to those in entire ewes at the time of oestrus. The esterified hormone was slower and more prolonged in action. Pretreatment with progesterone did not affect the vaginal changes, though it enhanced and hastened the onset of behavioural oestrus. The results are presumptive evidence that the greater dilatability of the ovine vagina at oestrus is an oestrogenic response.