The ovaries contain a large number of follicles, each of which encloses an ovum. Some of these follicles mature during the ovarian cycle, and the ova they contain progress to the secondary oocyte stage of meiosis. At ovulation, the largest follicle breaks open to extrude a secondary oocyte from the ovary. The empty follicle then becomes a corpus luteum, which ultimately degenerates at the end of a nonfertile cycle.
The two ovaries (fig. 20.25), about the size and shape of large almonds, are suspended by means of ligaments from the pelvic girdle. Extensions called fimbriae of the uterine (fallopian) tubes partially cover each ovary. Ova that are released from the ovary—in a process called ovulation—are normally drawn into the uterine tubes by the action of the ciliated epithelial lining of the tubes. The lumen of each uterine tube is continuous with the uterus (or womb), a pear-shaped muscular organ held in place within the pelvic cavity by ligaments.
The uterus consists of three layers. The outer layer of connective tissue is the perimetrium, the middle layer of smooth muscle is the myometrium, and the inner epithelial layer is the endometrium. The endometrium is a stratified, squamous,
Was this article helpful?
This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.