Reproductive system
I-Female reproductive system
The female reproductive system is composed of the ovaries and genital ducts external genitalia,
1- Ovary
Each ovary is a small, almond-shaped structure whose thick connective tissue capsule, the tunica albuginea, is covered by a simple squamous to cuboidal mesothelium known as the germinal epithelium. The ovary is divisible into a cortex rich in ovarian follicles and a highly vascular medulla.
Cortex
The cortex, located just deep to the tunica albuginea, houses the female germ cells, oogonia, which have undergone cell divisions to form numerous oocytes. Each oocyte is surrounded by a layer of epithelial cells, and these two structures together constitute an ovarian follicle. Under the influence of follicle stimulating hormone, follicles enlarge, are modified, become encapsulated by the ovarian stroma (connective tissue ), and mature.
Ovarian Follicles
The follicle passes through various maturational stages, from the primordial follicle, to the primary, the secondary, and finally, the Graafian (mature) follicle. The primordial follicle is composed of a primary oocyte surrounded by a single layer of flattened follicular cells. As maturation progresses, the follicular cells become cuboidal in shape, and the follicle is referred to as a unilaminar primary follicle. Multilaminar primary follicles display an oocyte surrounded by several layers of follicular cells and an intervening zona pellucida, as well as an externally positioned theca interna.
With further growth of the follicle, accumulations of follicular fluid in the intercellular spaces of the follicular cells form . At this point the entire structure is known as a secondary follicle, and it presents a well-developed zona pellucida, a clearly distinguishable basal membrane, and a theca interna and a theca externa.
As maturation progresses, the Graafian follicle stage is reached. This large structure is characterized by a follicular fluid contianing the central antrum whose wall is composed of the membrana granulosa . Jutting into the antrum is the cumulus oophorus housing the primary oocyte and its attendant zona pellucida and corona radiata . The Graafian follicle, mostly because of the activity of luteinizing hormone, rupturs, thus releasing the oocyte with its attendant follicular cells.