Experimental extension of the time interval between oocyte maturation and ovulation: Effect on fertilization and first cleavage

N. Dekel*, D. Ayalon, O. Lewysohn, N. Nevo, R. Kaplan-Kraicer, R. Shalgi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: To test the hypothesis that impaired fertility in human patients with high LH concentrations throughout the follicular phase of the menstrual cycle reflects premature maturation of their oocytes. Design: Previous information that resumption of meiosis is induced by lower hCG concentrations than that required for stimulation of follicular rupture was confirmed and used for establishment of a rat animal model in which oocyte maturation and ovulation can be separated experimentally. In further experiments hypophysectomized, pregnant mare serum gonadotropin (PMSG)- primed, immature female rats injected with 1.1 IU of hCG, a dose found to induce maturation in 72.9% ± 6% of the rats with no effect on ovulation, were administered with a second injection of an ovulatory dose (4 IU) of hCG, 24 hours later. The ovulated eggs were subjected to IVF. Results: Fertilization and first cleavage in oocytes recovered from our experimental animal model were similar to that observed in control PMSG-primed, either hypophysectomized or intact rats, treated by a single injection of 4 IU of hCG. Conclusions: The extension of the time interval between oocyte maturation and ovulation in the rat does not result in a lower rate of fertilization or a reduced incidence of cleavage. However, an inferior developmental capacity of these embryos cannot be ruled out.

Original languageEnglish
Pages (from-to)1023-1028
Number of pages6
JournalFertility and Sterility
Volume64
Issue number5
DOIs
StatePublished - 1995
Externally publishedYes

Keywords

  • LH surge
  • Oocyte maturation
  • delayed ovulation
  • fertilization

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