Observations on the Fine Structure and Relationships of the Chromatoid Body in Mammalian Spermatogenesis1

Abstract

The origin of the chromatoid body during spermatogenesis and its changing topographical relations to other components of the germ cells were studied in eight guinea pigs, four chinchillas, three Chinese hamsters, two rats, four mice, and one macaque. No evidence was found to support a nuclear origin of the chromatoid body. Instead, it seems to arise from the dense interstitial material that accumulates in the mitochondrial clusters of spermatocytes. In spermatids, it establishes an intimate but transient relationship with groups of nuclear pores, suggesting some kind of interaction between the chromatoid body and the nucleus. Migrating to the caudal pole of the nucleus, it forms a ring around the base of the flagellum and together with the annulus forms the structure called by classical cytologists, the "ring centriole." No clear morphological evidence was found indicating that the substance of the chromatoid body contributes directly to the formation of any of the structural components of the mature spermatozoon. It diminishes in size as it migrates with the annulus to the caudal end of the developing middle piece. There it disappears late in spermiogenesis apparently by disaggregation and dispersal of its subunits.