Transport of Eggs in Cumulus Through the Ampulla of the Rabbit Oviduct in Relation to Day of Pseudopregnancy

Newly ovulated eggs in cumulus, stained with toluidine blue, were transferred to the ampullae of the oviducts of (a) 5 rabbits at the time of ovulation, and thereafter at intervals of 24 hr for the 3 succeeding days, and (b) 21 does in estrus and at various times during induced pseudopregnancy. The mean times for the eggs to traverse the ampulla were 7.5 ± 0.7, 8.4±0.8 and 16.0±3.8 min in estrus, at ovulation, and on day 7 of pseudopregnancy, respectively. During this period the mean time of transport increased by 1.2 ± 0.28 min/day. This increase was highly significant. Owing to differences in oviduct lengths between rabbits, the rate of transport along the ampulla (mm/min) was felt to be a more valid measurement. The mean rates of transport were 11.4 ± 0.9, 8.9 ± 1.5 and 5.7 ± 0.8 mm/min in estrus, at ovulation and on day 2 1/2 of pseudopregnancy, respectively. During this period the mean rate of transport decreased by 2.36 ± 0.58 mm/min/day, a highly significant decrease. No further change was noted between day 2 1/2 and day 15 of pseudopregnancy. It is suggested that progestin has a depressing effect on muscular activity in the ampulla, which is reflected in the slower rate of transport, and that muscular activity is largely responsible for egg transport through the ampulla. Eggs in cumulus were not ejected from the ampulla of the estrous rabbit, which is contrary to the situation with denuded eggs. (Endocrinology77: 114, 1965)