The degeneration and disappearance of the centrioles during the development of the rat spermatozoon

Authors

  • David M. Woolley,

    1. Department of Anatomy and Laboratory of Human Reproduction and Reproductive Biology, Harvard Medical School, Boston, Massachusetts 02115
    Current affiliation:
    1. Department of Anatomy, Royal (Dick) School of Veterinary Studies, Edinburgh EH9 1QH, Scotland, U.K.
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  • Don W. Fawcett

    1. Department of Anatomy and Laboratory of Human Reproduction and Reproductive Biology, Harvard Medical School, Boston, Massachusetts 02115
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  • This work has been supported by the Ford Foundation and Contract NIH-69-2017 from the Center for Population Research, National Institute of Child Health and Human Development. One of the authors (D.M.W.) gratefully acknowledges the receipt of a Ford Foundation Fellowship.

Abstract

An intensive search has failed to locate a proximal centriole in the neck of the rat spermatozoon. This centriole is present in late spermatids but disappears before spermiation. The distal centriole also degenerates during spermiogenesis, though more gradually; it is no longer demonstrable by the time the spermatozoa reach the cauda epididymidis (except as a few remnants in a small minority of the cells). The rat spermatozoon is thus exceptional among mammals in being effectively acentriolate. The implications of this are discussed. Since there are no centrioles, the activity and control of the flagellum cannot depend on a centriole as a kinetic center. Furthermore, since no centrioles are introduced by the rat spermatozoon at fertilization, there can be no paternal inheritance of a formed centriole through the cytoplasm. And, in this species at least, paternal centrioles have no role in the first cleavage of the fertilized egg.

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