Ultrastructural studies of spontaneous spermiation in the guinea pig

Summary

This study describes, at the ultrastructural level, the cytological mechanisms operative in spontaneous spermiation in the guinea pig. At the beginning of stage VII of the spermatogenic wave, the mature spermatids lodge their heads each in an apical recess of the sustentacular cell, progressive widening of the cisternae of smooth endoplasmic reticulum and a moderate swelling of the cytoplasmic matrix obliterate the apical recesses, and the spermatids are then pushed away toward the tubule lumen.

Since these changes in the sustentacular cells affect solely their cytoplasmic areas immediately adjacent to the cluster of spermatid heads, and not the cytoplasmic areas surrounding the spermatids residual bodies, the latter remain imprisoned. Therefore, the stalk connecting each residual body to its spermatid, elongates to the point where it becomes severed at the moment when the spermatid is pushed away toward the tubule lumen.

These results are discussed in relation to the fluid current produced in the seminiferous tubules toward the rete testis.