Figure 3.

Exogenous E2 supplementation maintained cumulus cell competence to undergo expansion in vitro. Effects of exogenous E2 supplementation on viable cell number (D), maintenance of cumulus cell competence to undergo expansion (A and B), and expression levels of the cumulus expansion-related transcripts (C) were assessed. Freshly isolated COCs without maintenance culture treated with or without EGF were used as control groups (Fresh). A, Representative photographs of COCs before induction of cumulus expansion are shown as insets (0 h). Bar, 200 μm. Asterisks denote a significant difference between the two indicated groups (*, P < 0.05; **, P < 0.01). The values indicated by different alphabetical letters (a, b, c, and d) are significantly different (P < 0.05).