The Transport of Ova in Relation to the Dosage of Oestrogen in Ovariectomized Rabbits

Abstract

In order to determine what part the level of oestrogen in the body might play in the passage of ova through the female reproductive tract, 1249 freshly ovulated ova from donor rabbits were transferred into the uterine tubes of seventy-four ovariectomized recipients, fifty-three of which had previously been treated for 5-18 days with small daily injections of oestradiol benzoate. From 10 to 78 hr after transfer, 41 % of the ova were recovered from the uterine tubes, 9% from the uterine horns, and 23% from the vaginae of the recipient animals. Twenty-seven % of the ova were lost. The rate of ovum transport varied widely between similarly treated animals, and between the right and left sides of the reproductive tract of the same animal. Larger proportions of ova were retained in the uterine tubes, and smaller proportions in the uterine horns as the oestrogen dose was increased.The great variability in the stage of cleavage and in the thickness of the mucin coat of ova recovered from the uterus and vagina suggested that the ova might be widely dispersed through the uterine tubes and that they probably pass out of the uterine tube at widely different periods of time. Evidence is presented that ovum transport in ovariectomized rabbits with or without oestrogen treatment is very irregular, that ova may be ejected from either end of the uterine tube at almost any time after transfer, and that ova are not normally retained in the uteri of such animals.Approx. 1 \ g=m\ g oestradiol benzoate administered daily for 5-10 days was necessary to maintain the uterine weight of ovariectomized rabbits at about the same level as that in intact oestrous rabbits, and also to reduce the variability in egg transport observed in control and ovariectomized animals.Failure of the mechanisms that normally result in the transport of spermatozoa and ova through the female genital tract may be an important cause of reproductive loss in laboratory and farm animals. Considerable discrepancies between the numbers of ova ovulated and the numbers implanted have been reported in a wide variety of species (for review see Brambell [1948]). The studies of Hertig, Rock & Adams [1956] suggest that the failure of transport of the gametes may be the commonest cause of idiopathic infertility in women.The remarkable ability of the female genital tract to transport spermatozoa rapidly, though in restricted numbers, to the fertilization site in the uterine tube, and sub¬ sequently to transport the ova in the opposite direction, has been the subject of much study. The major factors involved in these processes are the relative sizes of the spermatozoa and ova, the motility of the spermatozoa, the action of tubai cilia, the contractility of tubai and uterine muscle, the secretion of cervical mucus and of tubai

Further Observations on the Effects of Oestradiol on Tubal Eggs and Implantation in the Guinea-Pig

“…Much of the experimental work has been done on the rabbit, where ovulation can be accurately timed (Courrier & Raynaud, 1934;Burdick & Pincus, 1935;Pincus & Kirsch, 1936;Csapo, 1955;Greenwald, 1957Greenwald, , 1959Noyes, Adams & Walton, 1959), but the rat, mouse, guinea-pig, cat and sheep have also been investigated (D'Amour, D'Amour & Gustavson, 1933;Dreisbach, 1959;Burdick, Whitney & Pincus, 1937;Kelly, 1931;Courrier & Gros, 1935;Robinson, 1951;Edgar & Asdell, 1960 Greenwald (1957Greenwald ( , 1959, Dreisbach (1959) Wintenberger (1955: sheep) and others have studied the normal passage of eggs and they agree that eggs pass fairly rapidly through the first part of the tube, and come to rest for at least a day in a less mobile region at some distance from the actual uterine junction. Since few eggs are recovered from the last part of the tube, it can be assumed that it is fairly rapidly traversed.…”

Mechanism of Anti-Implantation Action of Clomiphene

“…It is clear from our data shown in Table 1 (Noyes, Adams & Walton, 1959;Greenwald, 1961;Deanesly, 1963;Chang, 1964;Harper, 1964; and Lerner (1964) showed that clomiphene competes with oestrogen for binding sites in the uterus thus preventing the action of oestrogen injected subsequently. Shelesnyak (1957) has postulated that the pre-decidualization changes in the uterus are initiated by histamines which, in turn, are released by the action of oestrogens on the uterus; histamine-dependent decidual cell response may be prevented by antihistamines.…”

Intraperitoneal Insemination in the Rabbit

“…), rather than to an increased incidence of abnormal ova as they suggested. The unexpec¬ ted failure to recover eggs which should have been present in the tubes is thought to be due to their early destruction by excess spermatozoa, as previ¬ ously suggested by Noyes, Adams & Walton (1959). If (Moore, Adams & Rowson, 1968).…”