Pattern of Loss of Spermatozoa from the Vagina of the Ewe

Abstract

In a series of experiments spermatozoa were inseminated blindly into the vaginae of ewes and then recovered at varying times after insemination. Most of the spermatozoa inseminated were lost by drainage through the vulva. The rate of loss was not affected by the motility of spermatozoa or oestrous state of the ewe. Initially after insemination the loss was not rapid with 82% of the inseminate still remaining in the vagina after 3 h. After this time losses were very rapid and by 9 h after insemination 18% of spermatozoa remained and by 12 h 10% remained. Spermatozoa· were removed from the vagina during withdrawal of the penis after intromission and the extent of this loss varied between rams and with the volume of semen already in the vagina. Up to half the inseminate was lost in this way when there was o· 5 ml of semen in the vagina but only 11 % was lost when the volume of inseminate was 0·1 ml. The unavoidable loss of spermatozoa may influence the quantity available for fertilizing ova.