Biology of Reproduction, Vol 6, 98-108, Copyright © 1972 by Society for the Study of Reproduction

Ultrastructure of Annulate Lamellae in Primary Oocytes of Chimpanzees (Pan troglodytes)

¹ The Division of Pathobiology, New England Regional Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772 and The Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115

Three ovaries from 2 sexually mature chimpanzees in the midproliferative stage of their menstrual cycles were prepared for electron microscopy and 34 primary oocytes were serially sectioned. Stacks of 2-35 annulate lamellae were found in the cytoplasm of these oocytes, usually more than one in each cell. Those stacks cut in longitudinal section were contiguous with the nuclear envelope, and it appears that the annulate lamellae form from nuclear membrane. One or more of these stacks were frequently found in a crescent-shaped arrangement of organelles similar to the Balbiani body of human oocytes, while other stacks were distributed around the nucleus. The lamellar sheets enclose spaces of 64.5 nm, and contain pore-annular complexes like those of the nuclear envelope. The annuli of these complexes have an inner diameter of 60 nm and an outer diameter of 102.5 nm. The annuli are in register with those of adjacent lamellae and often with those of the nuclear membrane, suggesting passage of material from the nucleus to the cytoplasm. A large dense membrane-bound body may separate the stack of lamellae from the nucleus. The lamellae are usually continuous at their outer ends with other membranous elements, either disorganized tubules or endoplasmic reticulum, which may extend a great distance into the cytoplasm. The annulate lamellae in chimpanzees may break up to supply membrane elements to the cytoplasm, perhaps at the same time distributing nuclear material throughout the cytoplasm. The structure of the annulate lamellae in the chimpanzee are compared to those of other species, and several hypotheses concerning the origin and function of these organelles are discussed.