Relative RNA expression of Postn, AP-2, ζ-globin, Afp, and Tbx4 in extraembryonic tissues of (a) E8.5 and (b) E9.5 mouse embryos. Here, the relative RNA expression values were multiplied or divided by a scale factor, in order to represent values for different transcripts with different expression levels in a single graph. Expression levels of the different genes cannot be compared. Amnion is enriched in Postn and AP-2, while visceral yolk sac (Afp), allantois (Tbx4), and primitive red blood cell (ζ-globin) markers are neglectable. In contrast, yolk sac and allantois express low levels of Postn and AP-2. Abbreviations: Am: amnion; Al: allantois; YS: yolk sac.
