title: Effect of beta-mercaptoethanol during in vitro fertilization procedures on sperm penetration into porcine oocytes and the early development in vitro.
abstract: This study was carried out to determine the effects of beta-mercaptoethanol (bME) during a transient co-culture of gametes for 10 min, and/or the following culture until 6-9 h after insemination, on sperm penetration of porcine in vitro maturation (IVM) oocytes and the early development in vitro. When fresh spermatozoa were cultured in various concentrations of bME for 2 h, bME neutralized the stimulatory effect of caffeine-benzoate on sperm capacitation and the spontaneous acrosome reaction at 50-250 micromol/l. When 50 micromol/l bME were added during a transient co-culture of gametes for 10 min, the sperm penetration rate was reduced 9 h after insemination (70.5-82.0% vs 90.5-94.0% in the absence of bME), but the incidence of monospermic penetration was not affected. When 50 micromol/l bME were supplemented during culture after a transient co-culture, the sperm penetration rate was not affected, but the incidence of monospermy oocytes was increased (43.9-45.8% vs 31.7-34.3% in the absence of bME). The presence of bME following a transient co-culture minimized a decrease of oocyte glutathione content at 6 h after insemination (7.9 pmol/oocyte before in vitro fertilization (IVF), 6.7 pmol/oocyte in the presence of bME vs 5.5 pmol/oocyte in the absence of bME). When the distribution of cortical granules was evaluated 1 h after activation with calcium ionophore, mean pixel intensity of fluorescein isothiocyanate-labeled peanut agglutinin (FITC-PNA) at the cortex region was lower in the oocytes activated and cultured in the presence of 50 micromol/l bME. Although the presence of 50 micromol/l bME during a transient co-culture for 10 min and the following culture did not increased blastocyst formation (29.6-37.7%), 50 micromol/l bME during the following culture significantly increased the mean cell numbers per blastocyst (73.3-76.4 vs 51.2 in the presence and absence of bME respectively). These results demonstrate that supplementation with bME during IVF procedures, except during a transient co-culture period of gametes in the presence of caffeine, has a beneficial effect in maintaining the function of gametes, the incidence of normal fertilization and, consequently, the quality of IVF embryos.
authors.affiliation: The Graduate School of Natural Science and Technology, Okayama University, Tsushima-Naka, Okayama 700-8530, Japan. hirofun@cc.okayama-u.ac.jp
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Funahashi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001755:Blastocyst / Q000187:drug effects* / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D005260:Female; D005307:Fertilization in Vitro; D005978:Glutathione / Q000032:analysis; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008623:Mercaptoethanol / Q000494:pharmacology*; D008856:Microscopy, Fluorescence; D010312:Parthenogenesis; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D013552:Swine
chemical_list: D000975:Antioxidants; D003470:Culture Media; D007476:Ionophores; D002110:Caffeine; D008623:Mercaptoethanol; D005978:Glutathione; D002118:Calcium