Fig. 1. Allele-specific expression of the H19 imprinted gene in individual blastocysts. Gray bar height indicates the level of maternal expression, while black bar height represents the level of paternal-specific expression. The number of Whitten's cultured blastocysts with biallelic expression differed significantly from that of KSOMaa cultured (P=0.002), in vivo-derived (P=0.006), and B6XB6(CAST7) Whitten's cultured (P=0.0001) blastocysts as calculated by Fisher's exact test.