Control of germinal vesicle breakdown in bovine x murine hybrid oocytes.
Bovine oocytes cultured in control medium or in medium containing dibutyrylcyclic adenosine monophosphate (dbcAMP) or an inhibitor of cyclic nucleotide phosphodiesterase (3-isobutyl-1-methylxanthine, IBMX) undergo germinal vesicle breakdown (GVBD). On the other hand, mouse oocytes remain arrested at the germinal vesicle (GV) stage when dbcAMP or IBMX is present. When 1 bovine GV stage oocyte is fused to 1 GV stage mouse oocyte, dissolution of both species GV occurred in dbcAMP-supplemented medium. Only when 4 to 5 GV stage mouse oocytes are fused to 1 GV stage bovine oocyte, and these giant cells are cultured in dbcAMP-medium, is maturation arrested with only GVs present in the cytoplasm. The inhibitory effect is more evident in IBMX-supplemented medium. Here nearly 50% of the fused cells exhibit GVs, both mouse and bovine, when 1 cattle GV oocyte is fused to 1 mouse GV oocyte and the fused cells are cultured for 24 h. Moreover, nearly all GVs are well preserved after fusion of 1 bovine oocyte to 2 or more mouse oocytes. When these hybrid cells after 24 h culture in IBMX are then washed and cultured in control medium for a further 24 h, GVBD occurred in all cells. We are of the opinion that this novel approach (ie mixing of sensitive and non-sensitive cytoplasm) may in the future better explain the mechanisms involved in the regulation of mammalian oocyte maturation.
Fulka
J
J
Institute of Animal Production, Uhrínĕves, Czech Republic.
Leibfried-Rutledge
M L
ML
First
N L
NL
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002417:Cattle / Q000502:physiology*; D002478:Cells, Cultured; D005260:Female; D015726:Giant Cells / Q000502:physiology / Q000648:ultrastructure; D006822:Hybrid Cells / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D008540:Meiosis / Q000187:drug effects; D051379:Mice; D008813:Mice, Inbred ICR; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure
D003994:Bucladesine; D015056:1-Methyl-3-isobutylxanthine