Fig. 3. Gas1^-/- limbs display a delay in chondrogenesis and ossification. Whole-mount Alcian Blue (for cartilage) and Alizarin Red (for calcified bones) staining of control (con; A-F) and Gas1^-/- (-/-; A'-F') embryonic limbs (dorsal view) at the indicated stages. In all panels, digit I is on the left, and digit V, on the right, as labeled. Arrowheads indicate delayed cartilage condensation (A',B'); arrows, delayed or lack of phalangeal separation (C',D'); open arrows, delayed ossification of the phalanges (F'); open arrowheads, the normal size of ossification of the metacarpals (F,F'); m, metacarpal; p, phalange.