Figure 2.

Exogenous E2 supplementation promoted acquisition of competence to undergo expansion by PGOCs developed in vitro. PGOCs were cultured with or without exogenous E2 supplementation, and their competence to undergo expansion (A and B) and expression levels of the cumulus expansion-related transcripts (C) were assessed. In vivo grown complexes (i.e. COCs freshly isolated from large antral follicles) were used as control groups (in vivo grown). Arrowheads indicate clumps of unexpanded cells. Bar, 200 μm. The values indicated by different alphabetical letters (a and b) are significantly different (P < 0.05).