Pathology Thread

I. Gross Anatomy and Histology

1. Anatomy

The ovary is a firm, almond-shaped organ measuring about 3.5 cm long by 2 cm wide and 1 cm thick and attached to the back of the broad ligament by the mesovarium through which blood vessels pass to enter the hilum. It is attached to the pelvic wall by the suspensory ligament and the uterus by the ovarian ligament. In the nulliparous woman, the organ usually lies against the lateral pelvic wall. During pregnancy, the enlarging uterus pulls the ovary up into the abdominal cavity. After childbirth, when the broad ligament is lax, the ovary becomes quite mobile and its position then becomes variable.

The ovary is covered by a thin fibrous capsule, the tunica albuginea, and is smooth until puberty. Thereafter the surface becomes progressively scarred by degenerating corpora lutea making it irregular. After the menopause it becomes shrunken and its surface pitted with scars.

2. Histology

The ovary is covered by a low cuboidal epithelium, called the germinal epithelium (because it was wrongly thought to be the origin of oocytes). Beneath this epithelium is the tunica albuginea, which consists of collagen fibers and covers the outer zone, called the cortex. The cortex is highly cellular and contains follicles and corpora lutea and albicantia. This zone merges with the inner medulla without a clearly defined demarcation line. The medulla is smaller and contains loose connective tissue, occasional smooth muscle cells and numerous, tortuous arteries and veins.

The cortex contains spindle, fibroblast-like cells which give rise to the granulosa and theca cells, which are steroid producing cells and surround the germ cells to form primordial follicles. At birth, these are the only type of follicles present. After birth, a few primordial follicles at a time undergo further development to form primary follicles. After puberty, during each menstrual cycle several primary follicles begin to grow rapidly into secondary follicles but one, the dominant follicle develops faster than the rest to form the graafian follicle, which ruptures at ovulation. The other secondary follicles undergo follicular atresia. After ovulation the granulosa cells become luteinized and the follicle becomes the bright yellow corpus luteum. If fertilization and implantation fail to occur, the corpus luteum involutes, becomes white and forms the corpus albicans.