Fig. 6. Effects on spontaneous meiosis resumption or on HX-maintained meiotic arrest of the microinjection into the cytoplasm or into the GV of antibodies specific for the various cPKCs. (A) Control oocytes. Because PKC- is absent from the nucleus, anti-PKC- was used as a control for the microinjection procedure. The microinjection affected neither spontaneous meiosis resumption (-HX) nor maintained meiotic arrest (+HX). (B) Inhibition of the nuclear isoform of each cPKC except PKC- had a negative effect on spontaneous meiotic maturation. By contrast, the inhibition of the cytoplasmic isoforms of these enzymes had no effect on meiosis. (C) Top: oocytes were first cultured for 30 minutes, then microinjected into the cytoplasm and finally maintained in meiotic arrest by adding HX. Inhibition of the cytoplasmic isoforms affected meiotic arrest in different ways: the and ßII isoforms were not involved whereas the ßI and isoforms acted with HX to maintain meiotic arrest, the inhibition of these enzymes resulting in meiosis resumption. Bottom: oocytes were first cultured for 90 min, then microinjected and maintained in meiotic arrest by adding HX. Inhibition of the various cytoplasmic cPKC isoforms had no effect on meiotic arrest. The frequencies±s.e.m. of GVBD were calculated for at least three experiments. ^*, statistically significant difference versus control, P<0.05. White columns: control oocytes; gray columns: intracytoplasmic microinjection of the antibody; black columns: intranuclear microinjection of the antibody.