Extended Data Fig. 5: Development of the forelimb musculature of therian mammals with focus on the ventral extrinsic musculature.
From: Embryonic muscle splitting patterns reveal homologies of amniote forelimb muscles
Development of the forelimb musculature of therian mammals, Mus and Monodelphis, with focus on the ventral extrinsic musculature derived from the Pectoral (dark green) and Supracoracoideus (light green) divisions. The Pectoralis division originates M. panniculus carnosus (white bordered dark green arrow), M. pectoralis minor (empty dark green arrow) and the deep portion of M. pectoralis major (dark green arrow). The ventral portion of the Supracoracoideus division forms the superficial portion of M. pectoralis major (empty light green arrow) and the clavicular deltoid (light green arrow). The dorsal extension of the Supracoracoideus division invades the dorsal aspect of the scapula (*) and bifurcates around the scapular spine (**) originating M. supraspinatus (yellow bordered light green arrow) and M. infraspinatus (red bordered light green arrow). The upper series of mouse embryos depicts a medial view of stage E12.0, a lateral view of stage E12.5 and ventral views of E13.5 and 14.5. Bottom series of Monodelphis and Mus show the developing embryos with all muscle groups except for those deriving from the Pectoral and Supracoracoideus divisions removed, and the developing skeleton stained with either Sox9 or Col II antibodies. M. panniculus carnosus was removed from Monodelphis MC 33 and 33+ and Mus E14.5. dc: M. deltoideus clavicularis, isp: M. infraspinatus, pc: M. panniculus carnosus, PD: Pectoralis division, pmi: M. pectoralis minor, pmp: M. pectoralis major profundus, pms: M. pectoralis major superficialis, ssp: M. supraspinatus. All scale bars are 500 µm.
