Timing of in-vitro fertilization of cumulus-free and cumulus-enclosed human oocytes.
In humans, in contrast to other species, sperm capacitation requires a very short time, as in-vitro fertilization has been obtained after only 45 min of contact between oocytes and spermatozoa capacitated for 1 h. No fertilization occurred, whatever the duration of sperm capacitation, when gamete mixing did not exceed 30 min. On the contrary, 85% of cumulus-free mature oocytes exposed to sperm for 1-4 h were fertilized. The presence of the pre-ovulatory, fully-expanded or compact cumulus mass did not represent a physical barrier to sperm progression, as we observed no delay in fertilization when oocytes were enclosed in the cumulus. The use of a short insemination protocol (1-4 h instead of 17-20 h) did not reduce the fertilization rate of denuded or cumulus-enclosed oocytes and had no significant effect on the morphological appearance of the embryos or their cleavage rates.
D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D009865:Oocytes / Q000502:physiology*; D013075:Sperm Capacitation; D013997:Time Factors