In vitro fertilization of bovine oocytes in a chemically defined, protein- free medium varying the bicarbonate concentration

P. Tajik, W. H. Wang, K. Okuda, K. Niwa

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Bovine cumulus-enclosed oocytes were matured in culture, freed from cumulus cells, and inseminated with frozen-thawed spermatozoa in a chemically defined protein-free medium containing 5 mM caffeine and 10 μg/ml heparin. No penetration of oocytes was observed in the medium without polyvinylalcohol (PVA); but when the medium was supplemented with 0.1-5 mg/ml PVA, penetration rates (9-16%) significantly increased. Sperm motility was also stimulated during incubation for 2 h in the presence of PVA. In the medium with 1 mg/ml PVA, a high penetration rate (24 of 62 = 39%) was observed at a sperm concentration of 10 x 106 cells/ml. When the bicarbonate concentration was changed in the fertilization medium containing 1 mg/ml PVA and 10 x 106 spermatozoa/ml, a high penetration rate (47 of 67 = 70%) and a high proportion (44 of 47 = 94%) of oocytes in which male and female pronuclei had developed were obtained at 46 mM NaHCO3. However, the penetration rate (58- 95%), the incidence of pronuclear formation (64-96%), and the proportion of polyspermy (9-21%) varied according to the animal (five different bulls). Spermatozoa obtained from two bulls started to penetrate oocytes 5 h after insemination in the presence of 46 mM NaHCO3. This is the first report indicating that induction of capacitation of bull spermatozoa and penetration of oocytes matured in culture are possible in a chemically defined, protein- free medium.

Original languageEnglish
Pages (from-to)1231-1237
Number of pages7
JournalBiology of reproduction
Volume50
Issue number6
DOIs
Publication statusPublished - May 30 1994

ASJC Scopus subject areas

  • Reproductive Medicine
  • Cell Biology

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