Physiology of Finfish and Shellfish (2+1)

Yolk granules in oocyte

Oogonia the cells which are beginning to mature are surrounded by a single layer of epithelial cells, which are known as ovarian follicle. The epithelial cells which grow as the ovum grows and are separated from it by a gradually thickening hyaline capsule the zona pellucida.

The developing oocyte is located in the centre of follicle and is surrounded by follicle cells.

The follicle cell layer generally consists of an inner sublayer, the granulosa cell layer and one or two outer sublayer of theca cells. The theca and granulosa cell layers are separated by a basement membrane.

Generally as the oocyte grows there is increase in the yolk granule size of the oocytes.

Yolk nucleus is rich in protein, lipid, carbohydrate and Golgi bodies. Yolk nucleus provides the basic machinery for future vitellogenesis.