title: A comparison of the ultrastructure of spray-frozen and freeze-etched or freeze-dried bull and boar spermatozoa with that after chemical fixation.
abstract: The ultrastructure of bull and boar spermatozoa was investigated following different cryopreparation methods and chemical fixation. Spray-freezing was used for cryofixation in both freeze-etching and freeze-drying studies. Freeze-etching of boar spermatozoa revealed that the arrangement of the postnuclear striations differed from that in the bull. Freeze-drying gave excellent results for structural preservation, which were equal to those of chemical fixation. Some structural details not visible in chemically fixed cells were detected in freeze-dried and vacuum-embedded bull and boar spermatozoa, e.g. the arrangement of the lamellar nuclear contents, known from freeze-fractures, and a fine lamellar structure of the acrosomal contents. Cryofixation by spray-freezing combined with freeze-drying makes any contact of the cells with fixatives, buffer solutions and dehydration media unnecessary, and potentially provides all the advantages of ultrathin sectioning required for histochemical studies.
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000648:ultrastructure; D005404:Fixatives; D005407:Flagella / Q000648:ultrastructure; D005612:Freeze Drying; D005613:Freeze Etching / Q000379:methods; D008297:Male; D008854:Microscopy, Electron; D011309:Preservation, Biological / Q000379:methods*; D013094:Spermatozoa / Q000648:ultrastructure*; D013552:Swine
chemical_list: D005404:Fixatives