Uterine changes in experimental abortion and their relation to parturition

Abstract

RECENT work on the factors concerned in the initiation of parturition has demonstrated the importance of the ovarian hormone, cestrin, in determining those changes associated with the expulsion of the faetus [Robson, 1933b[Robson, , 1935aReynolds and Firor, 1933;Marrian and Newton, 1935], and has suggested that the cessation of lutealfunction is in itself not sufficient to elicit the changes typical of parturition [Robson, 1934b]. Indeed, it has been possible by the injection of oestrin during the later stages of pregnancy to induce alterations in the uterine reactivity to oxytocin similar to those obtaining at parturition, thus showing that the luteal function is by then largely in abeyance [Robson, 1935b].In the further investigation of the problem of parturition two important questions have arisen, namely:(1) Are the ovaries the only site of production of the ovarian hormones during pregnancy?(2) What extrinsic factors control the production of the ovarian hormones during pregnancy?With regard to the first question, the evidence that cestrin is secreted by organs other than the ovary during gestation appears to be conclusive for the human [Ask-Upmark, 1926] and the horse [Hart and Cole, 1934], but there is no evidence whether such is also the case in other species. In the human and the mare, and in addition in the guinea-pig, the corpus luteum is not essential during the whole of pregnancy, but with the exception of the finding by Adler, de Fremery and Tausk [1934] of progestin in the human placenta, there is no evidence as to whether the luteal hormone can be elaborated outside the ovary.It is well known that the secretory activity of the ovary is under the control of the anterior lobe of the pituitary, and there is much evidence

Regulation of the Gestation Period in Mice

“…Although the uterus of the mouse will respond to oxytocin at any stage of pregnancy, maximum sensitivity to oxytocin is attained only at parturition (Robson, 1934). Robson (1936) showed that removal of the ovaries on the 14th, 15th or 16th day of pregnancy in mice caused abortion, but did not alter the sensitivity of the uterus to oxytocin. However, ovariectomy on the 17th day did not cause abortion, but led to a very marked increase in sensitivity of the uterus to oxy¬ tocin.…”

Effect of the fetal placenta and of a rabbit pituitary extract on plasma progesterone in fetectomized rabbits

“…The corpora lutea comprise the sole significant source of progesterone (Thau & Lanman, 1974), and their maintenance in the second half of pregnancy requires the presence of both a pregnant uterus (Greep, 1941) and a maternal pituitary (Robson, 1936). In the absence of either of these, luteolysis occurs, and plasma progesterone production declines (Spies, Hilliard & Sawyer, 1968).…”