Abstract

The present study is a contribution to the knowledge of the ultrastructure of ovarian follicles in growth of the sheep of breed Algerian Rumbi. This last is characterized by parameters of reproductions very valuable and puberty seems to occur between 10 and 12 months with the onset of the first heat among lambs. The aim of the present study was to characterize the ultrastructural of Rumbi sheep preantral and antral follicle. Secondary follicle consisted of an oocyte surrounded by a variable number of layers of cuboidal granulosa cells. At this follicular stage, the zona pellucida with transzonales projections was beginning to form around the oocyte. The secondary follicle is characterized by the presence of a large nucleus; the endoplasmic reticulum is in the form of citernea dilated. The zona pellucida was totally developed around the oocyte. Several granulosa cell projections could be detected that were encroaching into the zona pellucida and protruding towards the oocyte, where gap junctions were observed between oocyte and granulosa cell membranes. Organelles within the oocyte were located at the periphery of the cytoplasm. Our results show that the tertiary and Graffian follicles are characterized by ultrastructural changes of their cellular organelles including the mitochondria and Golgi complex.

Key words: Follicles, preantral follicle, antral follicle, ovary, zona pellucida, sheep, rumbi sheep, Algeria.