a1 Institute of Animal Production, Prague, Czech Republic, The Babraham Institute, Cambridge, UK, and Department of Meat and Animal Science, University of Wisconsin, USA
Immature mouse oocytes (germinal vesicle stage, GV), oocytes at different stages during maturation (prometaphase to anaphase I) and matured oocytes (metaphase II arrested) were cultured in 6-dimethylaminopurine (6-DMAP)-supplemented medium also containing bromodeoxyuridine for the assessment of DNA replication in these cells. Immature oocytes remained arrested at the GV stage and DNA replication was never detected in them. On the other hand, oocytes at the prometaphase to anaphase-telophase I stages responded to 6-DMAP treatment by forming nuclei which synthesised DNA. Mature (metaphase II) oocytes did not respond to 6-DMAP and their chromatin remained condensed. DNA synthesis could even be induced in GV-staged oocytes, but only when they were fused to freshly activated oocytes and incubated in 6-DMAP-supplemented medium.
(Received March 20 1997)
(Accepted April 16 1997)
c1 J. Fulka, Jr, Institute of Animal Production, CS-104 01 Prague 10, Czech Republic. Tel: +42 2 67710659. Fax: +42 2 67710799.
1 Institute of Animal Production, CS-104 00 Prague 10, Czech Republic.
2 Babraham Institute, Department of Development and Genetics, Babraham, Cambridge CB2 4AT, UK.
3 University of Wisconsin, Department of Meat and Animal Science, Madison, WI 53706, USA.