Mesometrial smooth muscle in the mouse: Its control of uterine blood flows

Abstract

The form and function of the mesometrial smooth muscle and the interposed mesometrial branches and tributaries of the uterine vessels were studied in the nonpregnant and pregnant mouse to see whether contractions of mesometrial muscle alter uterine blood flows. Histological sections of mouse uterine horn demonstrated that the outer longitudinal layer of myometrium extends onto the mesometrium and sandwiches the mesometrium and its vessels as a bilaminar myometrial extension (BME). The BME ends midway across the mesometrium as a free edge. Cleared specimens, perfused with silicone rubber, revealed that the mesometrial branches and tributaries of the uterine vessels formed longitudinally communicating looping arcades between adjacent mesometrial vessels. Comparisons with human dissections and uterine histological sections revealed similar patterns of mesometrial smooth muscle and mesometrial blood vessels. BME activity and its control of mesometrial blood flow were studied by transillumination of the surgically exposed mesometria of anesthetized day 12 pregnant mice. Observed contractions of the BME coincided precisely with uterine contractions measured at the cervix and the BME contractions diminished or stopped venous outflow particularly in the midhorn regions. Arterial flows seemed to be unaffected and were diminished or halted only during infrequent forceful and sustained contractions. Trapped venous outflow passed up or down the venous arcades to escape through less restricted mesometrial veins. Uterine and BME contractions normally take place throughout gestation. It is possible that abnormally long and forceful contractions may compromise the embryo or fetus.

A Decellularized Uterine Endometrial Scaffold Enhances Regeneration of the Endometrium in Rats

“…The rodent uterus is connected to the dorsal body wall through heavy broad ligaments termed mesometria that contain blood and lymphatic vessels as well as abundant nerves [23]. Thus, uterine blood circulation is supplied through blood vessels bundled on the mesometrial side of the uterus [24].…”

Mesometrial smooth muscle as an origin of female retroperitoneal (pelvic) leiomyomas

“…Mossman [11] described in an anatomical study of the mammalian uterus that the development of mesometrial smooth muscle varies greatly between mammalian groups and that in some species, as in the porcupine, mesometrial smooth muscle forms a very conspicuous band. Liebgott [9] first studied the mesometrial smooth muscle systemically in the mouse and reported that the outer longitudinal myometrial layer extends onto the mesometrium as a bilaminar extension. This description corresponds to our observation in humans, while the mesometrial smooth muscle seems to be more developed in mice than humans [9].…”

“…Liebgott [9] first studied the mesometrial smooth muscle systemically in the mouse and reported that the outer longitudinal myometrial layer extends onto the mesometrium as a bilaminar extension. This description corresponds to our observation in humans, while the mesometrial smooth muscle seems to be more developed in mice than humans [9]. As expected, uterine myometrium and mesometrial smooth muscle are intimately related, but they do not appear identical.…”

DataSheet1.docx

“…In rodents, the bicornuate uterus consists of two uterine horns on the left and right sides. The uterine arteries are located on the mesometrium parallel to the extending uterine horns longitudinally and attached to one side of the uterus (Liebgott, 1984). In a transverse section of the uterus, the mesometrium and main uterine arteries protrude at one end of the circular tissue.…”