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. Author manuscript; available in PMC: 2018 Mar 1.
Published in final edited form as: J Cell Biochem. 2017 May 3;118(9):2941–2949. doi: 10.1002/jcb.25949

Figure 1. Diagram of ORC4 in Mouse Early Embryonic Development. (1) Normal Fertilization.

Figure 1

ORC4 is present in the cortex of GVBD oocytes (A), and coalesces near the chromosomes in metaphase I (B). ORC4 forms a cage around the chromosomes that are ejected in the first (C, D) and second (E, F) polar bodies. (E) The sperm chromatin forms a “sperm cone” which can be thought of as an abortive polar body that is reabsorbed by the oocyte by G1. (2) Parthenogenesis: ORC4 behaves the same way in parthenogenetically activated oocytes. BFA treatment of metaphase I (B) and metaphase II (D) oocytes results in the oocytes dividing into two equal sized cells and no polar body. The effects of BFA and Peptide injection are also shown. (3) Delayed Activation: Detergent washed sperm do not activate oocytes when injected. If activation by SrCl2 is delayed, the sperm chromatin is surrounded by ORC4 and ejected as a pseudo-polar body (F).