Aspects of vertebral development in lizards and snakes



The embryonic and postnatal development of vertebrae of the mid-trunk and mid-tail in Lacerta vivipara, Anguis fragilis and Natrix natrix have been studied. Centra and neural arches develop independently after the perichordal tube has been formed, the neurocentral suture representing a consistent boundary between them. The condyle and cup of each centrum are formed by differential growth of cartilage; in Anguis and Natrix the joints between centra are synovial. The zygosphenial joints of Lacerta are continuous with the zygapophysial joints and not separate from them as in snakes. The autotomy splits in the tail vertebrae of Lacerta are derived from four distinct components which become continuous in postnatal life. The chordal cartilage is not involved in the split formation.