Figure 2215

Photomicrograph of a human uterine tube. a. This cross section is near the ampulla region of the uterine tube. The mucosa is thrown into extensive folds that project into the lumen of the tube. The mus-cularis is composed of a thick inner layer of circularly arranged fibers and an outer layer of longitudinal fibers. Note several branches of

the uterine and ovarian arteries (BV) that travel along the uterine tube. X16. b. The lumen of the tube is lined by a simple columnar epithelium composed of ciliated cells (above the point of the arrow) and nonciliated cells (below the point of the arrow). X640.

surface where rupture will occur. As the oocyte is released, the ciliated cells in the infundibulum sweep it toward the opening of the uterine tube and thus prevent it from entering the peritoneal cavity. The oocyte is transported along the uterine tube by peristaltic contractions. The mechanisms by which spermatozoa and the oocyte are transported from opposite ends of the uterine tube are not fully understood. Research suggests that both ciliary movements and peristaltic muscular activity are involved in the movements of the oocyte. The movement of the spermatozoa is much too rapid, however, to be accounted for by intrinsic motility. Fertilization usually occurs in the ampulla, near its junction with the isthmus. The ovum remains in the uterine tube for about 3 days before it enters the uterine cavity. Several conditions that may alter the integrity of the tubal transport system (inflammation, use of intrauterine devices, surgical manipulation, tubal ligation) may cause ectopic pregnancies and are thus clinically important.

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