Spermiogenesis in action
This video shows spermatids undergoing spermiogenesis on a microscope slide in response to a chemical that was added to them. The clock shows elapsed time in minutes:seconds. Note how rapidly the entire transformation proceeds. The spermatid at the upper left fails to activate.
Note: In C. elegans, spermiogenesis is the final maturation of sperm, when the cell builds its pseudopod, acquires the ability to crawl, and becomes capable of fertilizing an oocyte. For a hermaphrodite's own sperm, spermiogenesis begins when the spermatids (the immature undifferentiated cells) arrive in the spermatheca, the chamber in the reproductive tract where fertilization will take place. Spermiogenesis of male spermatids is triggered upon mating. Spermiogenesis is a very rapid process; it only takes about 5 minutes to complete. During spermiogenesis, a set of dramatic cellular rearrangements take place, including plasma membrane flow at the site of the newly forming pseudopod, fusion of mysterious organelles, called membranous organelles, to the plasma membrane of the cell body, and the formation of a dynamic cytoskeleton in the pseudopod from the polymerization of a unique protein called the major sperm protein. Remarkably, all of these changes are accomplished without any new gene expression or protein synthesis, since spermatids lack transcription and translation machinery.
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