title: Penetration of porcine oocytes during maturation in vitro by cryopreserved, ejaculated spermatozoa.
abstract: The present study was conducted to examine the penetrability in vitro of immature porcine oocytes with or without cumulus cells. Porcine oocytes were cultured for 0-36 h, at 39 degrees C in 5% CO2 in air, in modified tissue culture medium 199 (TCM-199B at pH 7.4) supplemented with 10 IU eCG/ml, 10 IU hCG/ml, and 1 microgram estradiol-17 beta/ml. At various times after the beginning of culture, some oocytes were freed from the cumulus (cumulus and corona cells), and cumulus-intact or cumulus-free oocytes were inseminated with cryopreserved ejaculated spermatozoa in TCM-199B (pH 7.8) containing 5 mM caffeine. When cumulus-free oocytes were examined 14 h after insemination, high proportions (69-84%) were penetrated and there were no significant differences among different periods of maturation culture. The incidence (47-68%) of polyspermy and the number (1.7-3.1) of spermatozoa that penetrated per oocyte were also not significantly different among oocytes cultured for 0-36 h. In cumulus-intact oocytes, however, the first evidence of penetration (15%) was observed in oocytes cultured for 6 h. The penetration rates increased significantly as the period of culture was prolonged up to 24 h. Almost all (95-100%) oocytes were penetrated when they were inseminated 24-36 h after the beginning of culture, by which time the cumulus masses showed moderate to complete expansion except for the corona radiata. A similar correlation was also observed for incidence of polyspermy and number of spermatozoa penetrated per oocyte. The presence of well-expanded cumulus around the oocyte during fertilization promoted male pronuclear formation in penetrant oocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Division of Animal Science and Technology, Faculty of Agriculture, Okayama University, Japan.
authors.forename: W H
authors.initials: WH
authors.lastname: Wang
authors.forename: L R
authors.initials: LR
authors.lastname: Abeydeera
authors.forename: K
authors.initials: K
authors.lastname: Okuda
authors.forename: K
authors.initials: K
authors.lastname: Niwa
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D015925:Cryopreservation; D003470:Culture Media; D004542:Ejaculation; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D008297:Male; D009865:Oocytes / Q000502:physiology*; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology*; D013552:Swine / Q000502:physiology*; D013997:Time Factors
chemical_list: D006063:Chorionic Gonadotropin; D003470:Culture Media; D002110:Caffeine; D004958:Estradiol