Increased incidence of hematopoietic EBs from Smad5^−/− ES cells.

ES cells were plated into methylcellulose medium containing KL and IL-11 to form EBs. Note the extending hematopoietic halo surrounding the central cell mass of 85% Smad5^−/− EBs (A), whereas approximately 29% wild-type EBs ruptured with a few scattered hematopoietic cells (B) after 12 days of differentiation. Incidence of hematopoietic EBs was scored and values shown above each column represent the means ± SEMs from 3 independent experiments (C). Significance was determined using the Student t test: *represents data found to be significantly different from wild-type control values (P < .05); #, data found to be significantly different from heterozygous values (P < .05). Original magnification for panels A and B, × 40.