FORMATION OF THE SCAPULAR PART OF THE PECTORAL GIRDLE IN ANURAN LARVAE

The development of the scapular part of the pectoral girdle was traced from the limb bud stage to the metamorphosis climax in three anuran species of different families: Rana temporaria , Bufo bufo , and Bombina bombina . It was found that the scapular part originates from two independent anlagen — the «upper-scapular» and the «lower-scapular». These anlagen fuse together forming a unified cartilaginous element at the stage of young (nonhypertrophied) cartilage. The boundary between the definitive scapula and the suprascapula passes within the lower anlage. This boundary is a synchondrosis arising under the influence of m. interscapularis. The ratio of the scapula and the suprascapula length is determined by the place of m. interscapularis formation.