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.
Department of Anatomy and Developmental Biology, School of Medicine, Chiba University, Japan. fstoyota@med.m.chiba-u.ac.jp
F
F
Suzuki-Toyota
Y
Y
Itoh
K
K
Naito
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