Sul valore prospettico dello strato esterno e di quello interno della placca neurale di Rana esculenta. Esperienze di espianto

Rossi, Aldo

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 39 (1965) no. 1-2, pp. 136-142

Résumé

Explants from the external and internal layer of the multilayered neural plate were carried out on embryos of Rana esculenta at the stage of late gastrula-beginning of neural folds, with the following results: 1) the cells of the external layer of the neural plate displayed a greater histogenetic power than the cells of the internal layer. The nervous tissue cells differentiated from the cells of the external layer; 2) neuiral structures were formed both by the external and internal layer of the neural plate. The walls of such structures consisted of white matter, neuroblasts and differentiating neurons. The ventricles were delimited by embryonal ependyma likecells; 3) an eye may differentiate from the cells of the external and internal layer (anterior transverse neural fold and adjoining part of the neural plate); this eye was better differentiated if it originated from the cells of the internal layer; 4) the organization of the neural structures developed from the external layer was of the archiencephalic kind, while that one of the neural structures originated from the different parts of the internal layer of the plate was more strictly corresponding to that of the original site in the neural plate; 5) the growth of the neural structures derived from the explants of the external layer and of parts of internal layer of the neural plate was mainly due to the mitotic activity of the periventricular cells.