ISSN:
0148-7280
Keywords:
in vitro fertilization
;
electron microscopy
;
cortical reaction
;
zona reaction
;
monospermy
;
polyspermy
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
Cortical granule release and interaction with the zona pellucida are reported in monospermic and polyspermic fertilized ova and early human embryos cultured in vitro.Twenty-seven preovulatory oocytes from women with tubal or idiopathic infertility were recovered by laparoscopy, after induction of follicular maturation with clomid and human chorionic gonadotropin. These were then inseminated with husband's or donor sperm, cultured for 3-72 hr, routinely fixed in glutaraldehyde/osmium and examined ultrastructurally.Evidence of cortical granule release was observed in all ova and embryos investigated and their contents were identified either at the egg surface or in the perivitelline space or interacting with the inner zona, apparently reinforcing its structure. The latter is very likely the morphological expression of the zona reaction.Delayed release was seen in certain regions of normally fertilized ova and particularly in polyspermic ova, where massive “explosions” of granules occurred. This was attributed to delayed cortical maturation. The mechanics of release were similar in both monospermic and polyspermic ova. Spontaneous dehiscence was also described in one injured unfertilized oocyte.The significance of the cortical and zona reactions as an effective block to polyspermy at the level of the inner zona, which becomes more impenetrable to supplementary sperm, is discussed.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrd.1120060306
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