Fig. 6.

Tsg is epistatic over Cv2: the loss of Tsg in Cv2^−/− suppresses most of the Cv2 mutant skeletal phenotypes. Skeletal preparations of wild-type (A, E, I, M), Cv2^−/− (B, F, J, N), Tsg^−/− (C, G, K, O) and Cv2^−/−;Tsg^−/− (D, H, L, P) neonates stained with Alizarin Red and Alcian Blue. (A–D) The cervical neural arches (na) are reduced in Cv2^−/− but are rescued in Cv2^−/−;Tsg^−/− double mutants. The tracheal rings (tr) are missing in Cv2^−/− (red asterisk in B), but the tracheal (t) cartilage develops like wild-type (A) in Cv2^−/−;Tsg^−/− double mutants (D). (E–H). Cv2^−/− lack the humerus deltoid tuberosity (dt), which is rescued in Cv2^−/−;Tsg^−/−. (I–L) The posterior homeotic transformation of T13 (black asterisks) in Cv2^−/− (J) is rescued in Cv2^−/−;Tsg^−/− (L); however the ossification centers (oc) remain defective. (M–P) Side views of the lumbar region. Neural arches (na) are reduced in Cv2^−/− (N) but are only mildly affected in Cv2^−/−;Tsg^−/− (P), as is the case in Tsg^−/− mutants (O).