Sperm transport in the fowl

Abstract

(1) The distributions of living and dead sperm in the oviducts of hens a t various time intervals after artificial insemination were determined by using sperm labelled with ³²P and assaying the radioactivity of serial sections of the oviduct. Appropriate. tests of the method showed it to be valid and reasonably accurate for short-term experiments. (2) The number of sperm reaching the site of fertilization at the upper end of the oviduct (the infundibulum) was dependent primarily on where in the lower genital tract the sperm were deposited. Following intravaginal insemination with 2 X 10⁸ sperm, from 7 X 10³ to 70 X 10³ sperm were detected in the infundibula of different hens up to 1 hr after insemination. After intra-uterine insemination with a like number, from 137 X 10³ to 2642 X 1010³ sperm were detected. (3) The junction of the vagina and uterus (or shell gland) proved to be a barrier to sperm progress, as was shown by the greater efficiency of sperm utilization above the junction than below it. (4) Dead sperm inseminated intravaginally did not pass into the uterus but those inseminated into the uterus reached the infundibulum in as great numbers as a similar sample of living sperm. This suggested that the mechanism of sperm transport differs on either side of the uterovaginal junction. (5) From the speed of transport of sperm and the passage up the oviduct of sperm-free fluid injected into the uterus, it is suggested that the spasmodic contraction of muscle investing the wall of the upper vagina and lower uterus induced as a response to tactile stimuli is mainly responsible for sperm movement from the uterovaginal junction to the infundibulum. (6) Motility of sperm is necessary only to traverse the vagina and perhaps to penetrate the vitelline membrane of the egg during the process of fertilization. At other stages of movement between the vagina and the egg, sperm play a passive role in their own transport.