The uterine tube demonstrates active movements just before ovulation as the fimbriae become closely apposed to the ovary and localize over the region of the ovarian 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 (e.g., inﬂammation, use of intrauterine devices, surgical manipulation, tubal ligation) may cause ectopic pregnancy. The majority of ectopic pregnancies, 98% occur in the uterine tube (tubal pregnancies); remaining sites for the implantation of the blastocyst in ectopic pregnancies are the peritoneal cavity, ovaries, and cervix.
The uterus receives the rapidly developing morula from the uterine tube. All subsequent embryonic and fetal development occurs within the uterus, which undergoes dramatic increases in size and development. The human uterus is a hollow, pear-shaped organ located in the pelvis between the bladder and rectum. In a nulliparous woman, it weighs 30 g to 40 g and measures 7.5 cm in length, 5 cm in width at its superior aspect, and 2.5 cm in thickness. Its lumen, which is also flattened, is continuous with the uterine tubes and the vagina. Anatomically, the uterus is divided into two regions:  The body is the large upper portion of the uterus. The an terior surface is almost flat; the posterior surface is convex.
The upper, rounded part of the body that expands above the attachment of the uterine tubes is termed the fundus.  The cervix is the lower, barrel-shaped part of the uterus separated from the body by the isthmus (see Fig. 23.1). The lumen of the cervix, the cervical canal, has a constricted opening at each end. The internal os communicates with the cavity of the uterus; the external os with the vagina.
FIGURE 23.14 • Photomicrograph of a sagittal section of a human uterus. This section shows the three layers of the uterine wall: the endometrium, the innermost layer that lines the uterine cavity; the myometrium, the middle layer of smooth muscle; and the perimetrium, the very thin layer of peritoneum that covers the exterior surface of the uterus. The deep portion of the myometrium contains the larger blood vessels (BV ) that supply the uterus. 8.
The uterine wall is composed of three layers (Fig. 23.14).
From the lumen outward they are as follows.  The endometrium is the mucosa of the uterus.  The myometrium is the thick muscular layer. It is contin uous with the muscle layer of the uterine tube and vagina. The smooth muscle fibers also extend into the ligaments connected to the uterus.
 The perimetrium, the outer serous layer or visceral peritoneal covering of the uterus, is continuous with the pelvic and abdominal peritoneum and consists of a mesothelium and a thin layer of loose connective tissue. Beneath the mesothelium, a layer of elastic tissue is usually prominent.