Egg transport in ovariectomized rabbits as affected by different combinations of oestrogen and progesterone

A total of 1548 eggs was transferred to the oviducts of rabbits ovariectomized 45 days to 7 months earlier. The pattern of egg transport was disrupted, and the majority of eggs were in the vagina 60-72 h after transfer. To determine the role of the ovarian hormones on egg transport, the effects of various combinations of oestrogen and progesterone were studied. None of the hormonal treatments produced the normal transport pattern and large proportions of transferred eggs were retained in the oviducts. It is concluded that as long as progesterone is the dominant hormone, eggs move very slowly through the isthmus, and that a surge of oestrogen is required to modify the action of progesterone and to speed the movement of eggs to the uterus.