| Abstract: | The chromatoid body of rat spermatocytes and spermatids was studied with routine electron microscopy and the PA-silver method for detection of glycoproteins. The chromatoid body consists of a membrane-free aggregate of electron dense, finely filamentous material, in association with small vesicles. In late pachytene spermatocytes, there may be more than one chromatoid body; its dense component is diffusely reticulated. In young spermatids, there is only one chromatoid body per cell; the dense component is fairly compact, but it encloses less dense areas continuous with the cytoplasm. Within the less dense areas, as well as at the periphery of the dense component, small (400–800 Å) oval or tubular vesicular structures are observed whose contents exhibit a positive reaction for glycoprotein in PA-silver stained sections. When the spermatid nucleus begins to elongate, the chromatoid body takes the form of an arc around the axial filament proximal to the centriolar apparatus. Soon thereafter, the bulk of the chromatoid body condenses into a sphere of very dense filamentous material surrounded by a corona of enlarged glycoprotein-containing vesicles. In the later stages of spermiogenesis, the chromatoid body migrates away from the nucleus and disintegrates by fragmentation. It is noted that the chromatoid body undergoes its major morphological changes, possibly indicative of its active phase, while located in the para-centriolar region, at the time when the nucleus elongates, and the connecting piece and ring of the spermatid are formed. |
