Dissociation and Reaggregation of Embryonic cells of Triturus alpestris

C E L L movement and migration seem to play an important role in the formation of tissue-patterns during embryogenesis. Phenomena such as the appearance of loosely attached cells in the mesoderm, or of the freely migrating neural crest cells, are quite common in embryonic development. Since the tissues of adult organs are mostly rather compact in structure it seems that the capacity of isolated or loosely arranged cells to reassociate is an obligatory condition for many developmental processes. This capacity, under experimental conditions, was extensively studied by Holtfreter (1947, 1948). He has shown that cells of newt blastulae and early gastrulae can be made to dissociate and can then become reaggregated and proceed with their morphogenetic development. His experiments were carried out, for the most part, either with cells prior to histogenetic determination or with determined cells of a single tissue. Therefore no definite conclusion could be drawn from these observations as to whether in a reaggregate of cells from heterologous tissues the cells from each tissue will become reintegrated with their like and will differentiate according to their original presumptive fate, or whether regulatory modifications of differentiation occur in the aggregate. Moscona & Moscona (1952) described the formation of histological patterns from suspensions of cells obtained from multi-tissued organ rudiments of chick embryo. The experiment reported here is an attempt to investigate this question using isolated cells from newt neurulae, i.e. cells of tissues already determined and in which histogenesis has already started.