Table 1.

Some disparities between the oocytes and early embryos of Xenopus and Mus

Property	Xenopus	Mus	References
Mature oocyte volume	1 μl	270 pl	–
Spindle assembly checkpoint requirement for mII arrest	Yes	No	Tunquist et al, 2003; Tsurumi et al, 2004
Intact spindle requirement for maturation promoting factor destruction	No	Yes	Kubiak et al, 1993; Clute & Masui, 1995
Activation by pricking in Ca2+-containing medium	Yes	No	Wolf, 1974
Protein synthesis inhibition induces mII exit	No	Yes	Zhang & Masui, 1992; Siracusa et al, 1978
Cytostatic factor activity demonstrated by injecting cleaving blastomeres with (≥12% of their volume) mII ooplasm	Yes	No	Shibuya & Masui, 1988; Shoji et al, 2006
Oocytes support nuclear transfer cloning of adults from adult-derived somatic cells	No	Yes	Gurdon, 1960; Wakayama et al, 1998
Full chromatin decondensation requires activation	Yes	No	Yoshida et al, 2007
Activation accompanied by an increase in intracellular pH	Yes	No	Webb & Nuccitelli, 1981; Phillips & Baltz, 1996
[Ca2+]i oscillations induced by fertilization	No	Yes	Runft et al, 2002
Zygotic gene activation	4,000-cell stage	Late 1-cell stage	Aoki et al, 1997; Newport & Kirschner, 1982