Fate of the Neural Crest in Lampreys

Abstract

THE favourable nature of amphibian material has permitted the unequivocal demonstration, by both histological^1,2 and experimental^3,4 techniques, of the neural crest origin of most of the splanchnocranium and of the anterior portion of the trabeculæ cranii in these animals. In no other vertebrates is the position so clear; but in selachians⁵ and birds⁶ a similar origin has been claimed for the visceral bars as a result of studies of normal developmental stages. In cyclostomes the fate of the neural crest and the origin of the head skeleton is of particular interest in view of the doubt cast by Balfour on the homology of the visceral skeleton of lampreys with that of gnathostomes, and the suggestion of Sewertzoff and of de Beer⁷ that the ‘trabeculæ cranii’ of these animals are not visceral elements but are more properly regarded as anterior parachordals.