Experiments on the Neural Crest of the Lamprey Embryo

Abstract

1. The fate of the neural crest of the head in Lampetra planeri has been studied by experiments involving the removal or the homoplastic transplantation of short regions of this tissue. 2. The results show that the neural crest of lamprey is normally destined to form part at least of the dorsal root ganglia, and that it probably gives rise to most, if not all, of the melanophores and to some of the ectomesenchyme. 3. No evidence that the neural crest of the head was the source of the ‘trabeculae cranii’ or the cartilages of the branchial basket was found. It is concluded that these structures are most probably not crest derivatives. 4. The phylogenetic significance of the embryology of the lamprey ‘trabeculae cranii’ and visceral skeleton is discussed. 5. The transplantation experiments provided some evidence that the form of the neural tube in lamprey is determined in the same manner as that established by Holtfreter (1933, 1934) for Amphibia.