INDUCTION OF NUCLEAR DECONDENSATION OF MAMMALIAN SPERMATOZOA <i>IN VITRO</i>

Abstract

Department of Anatomy and Reproductive Biology, University of Hawaii School of Medicine, Honolulu, Hawaii 96822, U.S.A. (Received 10th December 1974) The nucleus of the mammalian spermatozoon is an exceptionally stable organelle requiring very rigorous chemical treatments to free its chromatin (Borenfreund et al., 1961). In spite of this, the nucleus swells and its chromatin begins to decondense very rapidly as the spermatozoon is incorporated into the egg cytoplasm (Austin, 1961; Yanagimachi &amp; Noda, 1970; Bedford, 1972). As yet, the mechanism underlying this phenomenon has not been directly examined. Various methods have been used to decondense sperm nuclei and to isolate and characterize the sperm chromatin and nuclear proteins (Borenfreund et al., 1961; Henricks &amp; Mayer, 1965; Lung, 1972). Sodium dodecyl sulphate (SDS, an anionic surfactant) and dithiothreitol (DTT, a reagent which specifically cleaves disulphide linkages) have been used to study nuclear stabilization during maturation of mammalian spermatozoa (Calvin &amp; Bedford,