ISSN:
0148-7280
Keywords:
zona-free hamster eggs
;
human sperm
;
in vitro sperm penetration
;
freeze fracture
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
An ultrastructural study has been carried out on the interaction of human sperm with zona-free hamster oocytes. Scanning, thin-section, and freeze-fracture electron microscopy were used to examine sperm in the process of contacting and fusing with the egg surface. Microvilli from the oocyte attach to the sperm head at anterior and posterior loci, initial contact often being made with the inner acrosomal membrane. Freeze-fracture study reveals that microvilli specifically contact particle-rich regions of the sperm head surface, and fusion with the oolemma occurs in the equatorial region of the spermatozoon. Intramembranous particle aggregation was observed on the postacrosomal and neck regions of spermatozoa and resulted from glutaraldehyde fixation and glycerolation, since fast freezing of unfixed specimens did not show patching. Counts of intramembranous particles on sperm head plasma membranes showed a reversal of the usual P face/E face ratios for unfixed, fresh sperm, whereas capacitated populations retained the usual particle distributions on P and E faces, even in unfixed, fresh samples. It is suggested that a switching of binding properties of integral proteins may occur during capacitation, resulting in a higher stability of the P-face association in unfixed cells.
Additional Material:
19 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrd.1120060409
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