[The induction of visceral cartilage from cranial neural crest by pharyngeal endoderm in hanging drop cultures and the locomotory behaviour of the neural crest cells during cartilage differentiation].

1. Cranial neural crest cells and pharyngeal primordia ofTriturus alpestris were cultured together by the hanging drop method at 20 °C. 2. In ca. 60% of the cases the foregut induced organotypic cartilage, procartilage and precursor stages. In most cases the cartilage tissues were in direct contact with the pharyngeal endoderm. 3. Besides cartilage, mesenchymal ganglionic cells, melanophores, xanthophores and epidermal epithelium developed from the neural crest cells. 4. In control cultures without pharynx endoderm no cartilage tissues were formed. 5. The locomotory behaviour of the neural crest cells prior to cartilage differentiation was analysed by a series of photographs. 6. During the first days in tissue culture neural crest cells behave like fibroblasts and show the phenomenon of contact inhibition. 7. As the first sign of their differentiation the presumptive cartilage cells in contact with the pharynx endoderm lose their motility. At a certain distance from the pharynx, however, neural crest cells do not change their locomotory behaviour. No attraction of cells by the endoderm could be observed. 8. In the course of further development the area of the presumptive cartilage cells contracts concentrically. The cells in its inner part become roundish, (chondrocytes). The cells in the peripheral part of the anlage become spindle-shaped (perichondrium). The chondrocytes form a hyaline cartilage matrix. 9. The rate of development and the quality of cartilage tissue differentiation depend on the density of neural crest cells at the beginning of the culture. 10. The results are discussed in relation to the change of affinities during differentiation.