Spermatid‐sertoli tubulobulbar complexes as devices for elimination of cytoplasm from the head region of late spermatids of the rat

Abstract The traditional and generally accepted mode of elimination of excess spermatid cytoplasm, known to take place at the time of sperm release, occurs as a result of the disengagement of the residual cytoplasmic mass. The present study suggests that cytoplasm is also eliminated from the head region of the spermatid in the period prior to sperm release. Data presented herein indicates that the amount of cytoplasm eliminated in this manner is substantial since the volume of spermatid cytoplasm diminishes by about 70% in the period of formation and resorption of tubulobulbar complexes. Reports from this laboratory (Russell and Clermont, '76; Russell, '79) indicated that characteristic evaginations of spermatid cytoplasm, termed tubulobulbar complexes , are resorbed by Sertoli cells in the form of numerous small pockets of cytoplasm. These pockets of cytoplasm are organelle‐free and show a “watery” consistency. They are subsequently degraded by the Sertoli cell prior to sperm release. During the period of turnover of tubulobular complexes the organelles of the cytoplasmic lobe, which at first are loosely organized, become clustered and tightly packed. As a consequence, the cytoplasmic lobe appears electron dense and is stained intensely with toluidine blue. This feature is interpreted, although not proven, to be the result of elimination of the watery component of the cytoplasm via resorption of tubulobulbar complexes by the Sertoli cell. During the period in which tubulobulbar complexes form, there is an open channel in which cytoplasm may flow from the flagellum to the head and out the head into tubulobulbar complexes.