Motile spermatid flagella during differentiation.

Flagella of living early human and rat spermatids show slight differences in duration of motion as revealed by phasecontrast microscopy and videotechnique. Wave-like motion of these 9+2-axonema becomes restricted to bending at later stages in the rat, whereas spermatozoa were found immotile in both species. Additional results were obtained from freely swimming spermatids of the rat and from the inner surface of rat seminiferous tubules, rinsed free of spermatozoa prior to scanning electron microscopy. Obviously, spermatids from some kind of flagellated cell layer that could be involved in liberating mature stages and in facilitating spermatozoa to glide more easily along seminiferous tubules.