Fig. 1. Esco2^fl/fl;Prrx1-Cre^Tg/0 mouse model of Roberts syndrome.

a P0 mice in dorsal and lateral views with indicated genotypes. Mutant mice present with phocomelia and craniofacial abnormalities including skull flattening and micrognathia. Scale bar: 5000 µm. b Hematoxylin and eosin (H&E) staining of coronal sections of Esco2^fl/fl (n = 3) and Esco2^fl/fl;Prrx1-Cre^Tg/0 (n = 3) forelimbs displayed in Fig. 1a. Scale bar: 1000 µm. Higher magnification of control and mutant forelimbs in outlined green boxes. Arrow points to islands of disorganized chondrocytes and palely amphophilic chondroid matrix. Humeral, radial, and ulna bones are unidentifiable in mutant compared to control pups. Scale bar: 5000 µm. c Gross morphology of E9.5–E13.5 embryos post-harvesting with indicated genotypes. Notably smaller limbs with hemorrhaging in mutant compared to control embryos. Dashed white line outlines E11.5 forelimb with edema. Scale bar: 1000 µm.