Fig. 6.

Endogenous BMP signaling prior to BMP4 treatment is required for surface ectodermal differentiation. (A-C) Representative images of colonies immunostained for the indicated antibodies on day 3 following induction in media containing SB only or in combination with LDN (A), and on day 6 following 1, 2 or 3 days of SB+LDN treatment in the first phase of induction prior to BMP4 treatment for 3 days. Conditions that removed dual inhibition before day 3 had media replaced with N2B27+SB such that all conditions were in culture for the same duration prior to the introduction of BMP4 (B). Experiments were repeated three (A) and four (B) times. Colony diameter: 800 µm (A); 700 µm (B). Scale bars: 100 µm.