Colony-forming potential of Scl^-/- FLK-1⁺ EB-derived cells. (A) Blast colony (□) and core colony (▦) development from FLK-1⁺ day 3 Scl^+/+ and day 3.5 Scl^-/- EBs. Data are presented as mean number of blast colonies and cores per 10⁵ input cells from 3 dishes. (B) Photographs of Scl^+/+ blast colonies and Scl^-/- cores at day 2 and 3 of development. Original magnification, × 200. Objective × 20, numerical aperture 0.30. MagnaFire software was used to analyze the images. (C) RT-PCR analysis of Scl^+/+ (+/+) and Scl^-/- (-/-) colonies at days 2 and 3 of growth. Each lane represents a pool of 500 colonies. Hybridization was carried out with probes designed against the 3′ UTR of the indicated genes. (D) Immunohistochemistry of adhesive cells generated from Scl^+/+ blast colonies (Scl^+/+) and Scl^-/- cores (Scl^-/-). CD31⁺ (red) and SMA⁺ (green) populations are indicated. Original magnification, × 200. Objective × 20, numerical aperture 0.70. OpenLab software was used to analyze the images.