Utero-oviductal motility with emphasis on ova transport.

Abstract

Listen

Translate article

Utero-tubal motility in vivo has been observed in conscious animals by several methods. In women cyclic variations have been seen. As ovulation approaches the activity increases. In vitro motility was maximal in myometrial strips from estrous ewes intermediate in strips from ovariectomized ewes and least in strips taken during the luteal phase. It has been thought that estrogen stimulates and progesterone suppresses oviductal muscular contractility. This has been disproved. A relationship between the activity of the oviduct and of the uterus has not been shown in women. Experiments indicate that prostaglandins are involved in the regulation of the oviductal function and of the uterine musculature. Other possible effects of prostaglandins are thought to occur. In women oxytocin and vasopression exert their maximal responses in the utero-ovarian motility during the late luteal phase and during menstruation. Both epinephrine and norepinephrine have stimulatory effects on oviductal activity throughout the cycle but least during the luteal phase. The uterine musculature responds differently to the effects of epinephrine and norepinehprine being more relaxed under epinephrine. The pacemaker of oviductal contractions has been localized in a discrete area around the ampullary-isthmic junction. Uterine activity is myogenic. Myometrial pacemaker activity is not confined to a distinct anatomical area. Impulses are conducted through the uterine muscle in a wavelike pattern and are propagated equally in all directions. The mammalian oviduct is a dynamic structure. It is not a passive conduit for the gavetes. The progress of spermatozoa in 1 direction and the transport of ova in the opposite direction are primarily controlled by the coordinated action of peristaltic antiperistaltic and segmental waves of contraction. The stream of oviductal secretions and the rhythmic beat of cilia are also important. Oviductal and uterine smooth musculature are under the control of the secretions of the corpus luteum. The utero-tubal junction is a transitional zone. In women the intramural portion of the oviduct has a convoluted course and varies in length from 1 to 3.5 cm. It acts in concert with the uterus and the isthmic portion of the oviduct. The progressive movement of ova is temporarily arrested 1-2 cm from the uterus. Ova then pass rapidly through the utero-tubal junction. A timed delivery of the fertilized ovum is of critical significance for normal implantation. In some sterile dysmenorrheic women as isthmic spasm has been demonstrated and assumed to have caused the sterility. Contraceptive drugs profoundly affect the myometrial cycle by changing the regulatory system. IUDs have been shown to cause altered oviductal function.