SUMMARY
A study was made of the effect of ligating the Fallopian tube or uterine horn near the tubouterine junction at specific time intervals after mating (½–6 hr) on fertilization in superovulated rabbits. A total of 140 does were used and altogether 2630 eggs were studied. Observations were made on the does' response to gonadotrophin treatment; the rate of egg development; the occurrence of abnormal eggs; the number of spermatozoa in fertilized eggs; the transfer of fertilized eggs to recipient does and the length of the female genital tract. Rabbit semen was collected by means of an improved type of artificial vagina.
The main results following ligation were as follows: when one Fallopian tube was ligated at the time intervals stated in parentheses, the mean proportion of eggs fertilized was 1·6% (1¼ hr), 8·8% (1¾ hr), 12·9% (2 hr), 16·1% (2¼ hr), 29·8% (2½ hr), 59·5% (2¾ hr), 85·9% (3 hr), 38·4% (3¼ hr), 73·7% (3½ hr), 50% (4 hr), 96·4% (5 hr) and 100% (6 hr). Out of a total of 1006 eggs from non-ligated (control) Fallopian tubes, 95·5% were fertilized. Following ligation of one uterine horn 30 min, 1 hr or 2 hr after mating, 9·1, 38·7 and 55·2%, respectively, of the eggs were fertilized.
It is concluded that although some spermatozoa may reach the tubo-uterine junction soon after mating, 2–5 hr are required before the number of spermatozoa entering the Fallopian tube is sufficiently high to produce maximum fertilization.
