Figure 5

Meiotic progression and pronucleus formation in the MII-oocytes from XX and XY females following parthenogenic activation. (A) Time-lapse microscopy analysis of the second meiotic division. Chromosomes were stained with Hoechst 33342 (blue) at the end of time-lapse imaging. Five types of oocytes are shown; (1) a typical oocyte from an XX female with extrusion of the second polar body and single pronucleus formation. The oocytes from XY females are seen (2) without the second polar body extrusion and with two pronuclei formation, (3) with extrusion of the second polar body and two pronuclei formation, (4) without the second polar body extrusion and with multiple pronuclei formation, or (5) with symmetric cell division. Bar: 20 µm. (The time-lapse videos are given in Supplementary Fig. S2.1–S2.5) (B) Percentages of oocytes with the second polar body extrusion. (C) The time required for the oocyte to initiate the first polar body degradation, the second polar body extrusion, and pronuleus formation. (D) Percentages of oocytes that formed different numbers of pronuclei. Data are presented as mean ± SEM. * and **, significant differences between the oocytes from XX females and those from XY females at p < 0.05 and 0.001, respectively. The experiments were repeated at least three times each. For the in vivo maturation, total 67 and 63 oocytes from XX and XY females, respectively, were examined. For IVM, total 89 and 99 oocytes from XX and XY females, respectively, were examined.