(A–F) Zygotes were created by transferring S phase pronuclei into S phase parthenotes, as in Fig. 4A (arrow in D–F indicates pronuclear fragment that was transferred in this oocyte that continued to replicate); (G–L) G1 pronuclei into S phase ooplasm in parthenotes, as in Fig. 4B; (M–R) or by transferring S phase pronuclei into G1 ooplasm in parthenotes, as in Fig. 4C. The zygotes were then incubated in BrdU for 30, 3 hr or 4 h, as indicated on the left hand panel, then fixed and stained for BrdU incorporation and DNA with propidium iodide. Phase contrast, BrdU staining and propidium iodide staining are shown, as indicated. Bar = 20 µm.