The chromatoid body in mouse spermatogenesis: Evidence that it may be formed by the extrusion of nucleolar components

Abstract

The chromatoid body is an intensely staining cytoplasmic organelle which is present during spermiogenesis of many eukaryotes. The present fine structure studies of this body in the testes of the mouse show that it is first apparent in the cytoplasm of pachytene and diplotene cells and is located in the immediate vicinity of the nuclear membrane. At this stage the chromatoid body is usually adjacent to similar staining intranuclear material which is probably of nucleolar origin. The fully developed chromatoid body has the same staining reaction, texture, and multilocularity as does a portion of the nucleolus of pachytene and diplotene cells. Numerous precedents exist in other organisms for a similar extrusion of nucleolar material into the cytoplasm in both interphase and meiotic cells. These observations provide support for the early proposal that the chromatoid body is derived from intranuclear and probably nucleolar material.