title: Differences in pronucleus formation and first cleavage following in vitro fertilization between pig oocytes matured in vivo and in vitro.
abstract: To elucidate the developmental differences occurring after in vitro fertilization (IVF) of pig oocytes matured either in vitro (n = 1934) or in vivo (n = 1128), the present experiment investigated the morphological changes from penetration to the two-cell stage. Oocytes were examined every 2-4 h from 2 to 32 h after in vitro insemination to study sperm penetration, male and female pronucleus formation, synkaryosis and first cleavage. The penetration rate was significantly higher (P < 0.05) for in vivo matured oocytes (69.8%) than for in vitro matured oocytes (35.0%). Penetration of spermatozoa into the ooplasm was first recorded 6 h (in vitro matured oocytes) and 4 h (in vivo matured oocytes) after addition of the spermatozoa to the oocytes. For both in vivo and in vitro matured oocytes, 2 h were required for sperm head decondensation. However, maximum sperm head decondensation occurred 2 h later in in vitro matured oocytes. Within 6 h, 41.7 +/- 5.6% of the in vivo matured oocytes had completed second meiotic division, whereas only 20.8 +/- 6.5% of the in vitro matured oocytes reached this developmental stage (P < 0.01). For in vitro matured oocytes, male pronucleus formation was retarded 2-4 h after onset of insemination and development of the female pronucleus was enhanced compared with in vivo matured oocytes. Synchronized opposing pronuclei were observed 14 h after insemination in in vitro matured oocytes and after 8 h in in vivo matured oocytes. Synkaryosis was first observed at 16 and 18 h in in vivo and in vitro matured oocytes, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Research Institute of Animal Production, Nitra, Slovak Republic.
authors.forename: J
authors.initials: J
authors.lastname: Laurincik
authors.forename: D
authors.initials: D
authors.lastname: Rath
authors.forename: H
authors.initials: H
authors.lastname: Niemann
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002970:Cleavage Stage, Ovum; D005260:Female; D005307:Fertilization in Vitro; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D009866:Oogenesis / Q000502:physiology; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology; D013552:Swine / Q000502:physiology*; D013997:Time Factors