Reduction of intramembranous particles in the periacrosomal plasma membrane of boar spermatozoa during in vitro capacitation: a statistical study.
Membrane remodeling in the periacrosomal plasma membrane (PAPM) of boar spermatozoa during incubation in capacitation medium was examined by the freeze-fracture technique. In the preservation medium (PM) group, the major small (about 8 nm) intramembranous particles (IMP) and the minor large (> 10 nm) IMP were distributed evenly in the PAPM. The IMP-free area increased during capacitation. To correct the IMP-free area, arithmetically redistributed (ARD)-IMP density was used for statistical analysis. In the PM group, the mean density +/- SD of large IMP was 379 +/- 64 and 266 +/- 58/microm2, and that of small IMP was 1450 +/- 155 and 672 +/- 252/microm2 in protoplasmic (P) and external (E) faces, respectively. During capacitation, the significant (P < 0.01) reduction of large IMP density was encountered only in the E face of a few incubation groups, while that of the small IMP density occurred in the P face by 2 h. Consequently, reduction of the total IMP density of both faces was not significant in the large IMP, but it was significant (P < 0.01) in the small IMP. One-fifth of the total small IMP density reduced by 2 h. Filipin-sterol complexes (FSC) were numerous in the PAPM, and FSC-free areas also increased during capacitation. The mechanism of IMP-free area formation and the behavior of the small IMP in the PAPM during capacitation were discussed in relation to membrane stability.
Suzuki-Toyota
F
F
Department of Anatomy and Developmental Biology, School of Medicine, Chiba University, Japan. fstoyota@med.m.chiba-u.ac.jp
Itoh
Y
Y
Naito
K
K
D000177:Acrosome / Q000502:physiology / Q000648:ultrastructure*; D020101:Acrosome Reaction / Q000502:physiology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D003627:Data Interpretation, Statistical; D005372:Filipin / Q000494:pharmacology; D005614:Freeze Fracturing; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000502:physiology / Q000648:ultrastructure; D008297:Male; D013075:Sperm Capacitation / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology / Q000648:ultrastructure*; D013552:Swine
D000900:Anti-Bacterial Agents; D005372:Filipin