Maturation ability of rat oocytes with different chromatin configurations.

cNSN: prematurely condensed non-surrounded nucleolus, COC: cumulus–oocyte complexes, cSN-1: prematurely condensed surrounded nucleolus, NSN: non-surrounded nucleolus, pNSN: partly non-surrounded nucleolus, pSN-1: partly surrounded nucleolus, SN-1: surrounded nucleolus, SN-2: aggregated. ^a–e: There are significant differences between items with different letters in the same column (P < 0.05). Each treatment was replicated 3–4 times, and each replicate included approximately 20 COCs. (DOCX)