Studies on the human oocyte and its follicle. I. Ultrastructural and histochemical observations on the primordial follicle stage.

Oocytes in primordial ("resting") follicles in adult human ovaries contain a complex paranuclear structure identified by light microscopists as Balbiani's vitelline body. By electron microscopy this structure is composed of a mass of mitochondria with associated endoplasmic reticulum, multiple compound aggregates which form a ring around the cytocentrum, and a single stack or coil of annulate lamellae either attached to the nuclear membrane or free in the cytoplasm. The compound aggregates contain vacuoles and finely divided electron-opaque material.

STUDIES ON GUINEA PIG OOCYTES. I. ELECTRON MICROSCOPIC OBSERVATIONS ON THE DEVELOPMENT OF CYTOPLASMIC ORGANELLES IN OOCYTES OF PRIMORDIAL AND PRIMARY FOLLICLES.

Oocytes in primordial and primary follicles of young adult guinea pig ovaries fixed in osmium tetroxide and embedded in Epon 812, have been observed by electron microscopy. The gradual differentiation of a series of cytoplasmic organelles has been correlated with the growth in size of the oocyte and the development of the follicular wall. The most immature primordial oocyte is morphologically a simple cell consisting of a large slightly eccentric nucleus, a few large spherical mitochondria, a profusion of granular cytoplasmic vesicles, and free RNP particles.