Each ovary is attached to the dorsal abdominal wall through mesovarium and ovarian ligament. Through this attachment numerous blood vessels and lymphatics enter into or emerge from the ovary.
Each ovary is principally composed of stroma of fibrous connective tissue and is lined externally at its free surface by a germinal epithelium of cuboid epithelial cells.
The germinal epithelium proliferates thousands of primordial follicles during the embryonic life of an individual but less than a tenth per cent mature in the life of the individual and remainder degenerate into atretic follicles.
Each ovary is roughly differentiated into an outer cortex and an inner medulla. Although these two regions appear to contain distinct structures, there is no demarcation line between them in the mature ovary.
In mature ovary the cortex contains follicles and corpora lutea in various stages of differentiation and disintegration.
The medulla contains only the large blood vessels of the organ. During the growth of the ovary the germinal epithelium at various places dips into the body of ovary, and by the growth of the connective tissue of stroma a mass of epithelial cells becomes separated from the main layer.
One cell of this mass gives rise to an immature ovum or oocyte; the remaining cells form a layer surrounding the ovum or oocyte as sac or follicle called follicular epithelium or granulosa.
Immature ovum or oocyte and surrounding follicular epithelium or granulosa constitute the primordial follicle.
The stroma of the ovary surrounding the follicular epithelium or granulosa becomes organized into connective tissue lavers, the theca externa and the theca interna.
Theca interna in case of man serves as a glandular and vascular oestrogen synthesizing layer.