The female reproductive system includes the labia minora and the recto-uterine pouch of douglas. The anatomy and histology of the ovary are shown in Figure 44.13 and Figure 44.14, respectively. The ovary consists of a layer of simple epithelium made up of ovarian surface epithelial cells. Unlike other organs, the ovary does not have ducts to transport its gametes to the reproductive tract. Instead, ovulation occurs through an inflammatory process that damages the ovarian wall, which is then repaired by the rapid division of ovarian surface epithelial cells. Most cases of ovarian cancer originate from this highly proliferative epithelium.

The functional unit of the ovary is the ovarian follicle, which carries out both gametogenic and endocrine functions. In a premenopausal cycling woman, the ovary contains follicular structures at various stages of development. The life cycle of a follicle can be divided into several stages, including the primordial follicle, primary follicle, secondary preantral follicle, dominant (preovulatory, graafian) follicle, dominant follicle within the periovulatory period, and corpus luteum (of menstruation or of pregnancy) (Figure 44.15). 

The development of a primordial follicle into a secondary preantral follicle involves the interaction between gametes and somatic cells. Primordial germ cells, which migrate to the gonad, divide mitotically as oogonia until the fifth month of gestation in humans. At this stage, the oogonia undergo meiosis and become primary oocytes. These primary oocytes are then surrounded by a simple epithelium of somatic follicle cells, forming the primordial follicles. The follicle cells establish gap junctions with each other and the oocyte. They represent an avascular epithelium surrounded by a basal lamina. Some granulosa cells remain attached to the oocytes and provide nutrients such as amino acids, nucleic acids, and pyruvate for oocyte maturation (Figure 44.15).

The primordial follicles serve as the ovarian reserve of follicles.
Labia minora Recto-uterine pouch of douglas • Fig. 44.13 Anatomy of the female reproductive system. (Modified from Drake RL et al. Gray’s Anatomy for Students. Philadelphia: Churchill Livingstone; 2005.) • Fig. 44.14 Histology of the ovary. CL, corpus luteum; F, follicle. (Modified from Young B et al. Wheater’s Functional Histology. A Text and Colour Atlas. 5th ed. London: Churchill Livingstone; 2006.) and a layer of simple epithelium consisting of ovarian surface epithelial cells. There are no ducts emerging from the ovary to convey its gametes to the reproductive tract. Thus the process of ovulation involves an inflammatory event that erodes the wall of the ovary. After ovulation the ovarian surface epithelial cells rapidly divide to repair the wall. The majority of ovarian cancer originates from this highly proliferative epithelium.
Growth, Development, and Function  of the Ovarian Follicle
The ovarian follicle is the functional unit of the ovary, and it performs both gametogenic and endocrine functions. A histological section of the ovary from a premenopausal cycling woman contains follicular structures at many different stages of development. The life history of a follicle can be divided into the following stages: 1.
2.
3.
4.
dominant (preovulatory, graafian) follicle 5.
dominant follicle within the periovulatory period 6.
corpus luteum (of menstruation or of pregnancy) 7.
Fig. 44.15 ) represent the earliest and simplest follicular structure in the ovary. Primordial follicles appear during midgestation through the interaction of gametes and somatic cells. Primordial germ cells that have migrated to the gonad continue to divide mitotically as oogonia until the fifth month of gestation in humans. At this point the approximately 7 million oogonia enter the process of meiosis and become primary oocytes. During this time the primary oocytes become surrounded by a simple epithelium of somatic follicle cells, thereby creating the primordial follicles (see
Fig. 44.15 ). The follicle cells establish gap junctions with each other and the oocyte. The follicle cells themselves represent a true avascular epithelium surrounded by a basal lamina. Similar to Sertoli cell–sperm interactions, a subpopulation of granulosa cells remains intimately attached to the oocytes throughout their development. Granulosa cells provide nutrients such as amino acids, nucleic acids, and pyruvate to support oocyte maturation.
•Fig. 44.15 Developmentofaprimordialfollicleuptoasecondarypreantralfollicle.(ModifiedfromWhiteBA,PorterfieldSP.Endocrine Physiology. 4thed.Philadelphia:Mosby;2013.)Primordial follicle Primary oocyte Basal lamina Pregranulosa cells Germinal vesicle with nucleolus Zona pellucida Cuboidal granulosa cells Primary follicle Secondary preantral follicle Theca Stratified granulosa cells
The primordial follicles represent the ovarian reserve of follicles (