Uterine microcirculation in common tree shrew as revealed by scanning electron microscopy

Abstract

The microvasculature of the common tree shrew uterus has been studied using vascular corrosion cast technique/ SEM with complementary application of routine paraffin technique and conventional SEM. It is found that the arterial blood supply to the common tree shrew uterus was from two main sources, the uterine and ovarian arteries forming utero-ovarian anatomosis which gives rise to the segmental arteries. The segmental artery takes a tortuous course before giving rise to arterial arcades and arterial networks. It also gives off branches running dorsally and ventrally around the uterus being the circumferential arteries which anatomose each other at the antimesometrial border and gives off radial branches to supply the endometrium. Before reaching the endometrium, the radial artery usually gives off fine branches coursing circularly to form the incomplete circle surrounding the endometrium, and finally become the subepithelial capillary plexus. The capillaries in the endometrium and myometrium drain the venous blood into the circumferential veins before becoming larger veins called the segmental veins. With conventional SEM, it is found that the endometrial surface is covered with two types of simple columnar cells, the ciliated cells and microvillous cells. Ciliated cells are oftenly located near the ostia of the uterine glands but very few of them are found along the mesometrial as well as antimesometrial borders or middle portion of the uterine horns. The tree shrew exhibit morphological link between nonprimate and primate species. Eventhough, uterine vasculature of common tree shrew has not been studied in relation to the sexual cycle, it is expected that the density and the pattern of endometrial vascular supply are varied depending on the estrogen and progesterone levels.