ABSTRACT
The relation between certain transverse bulges of the wall of the central nervous system (proneuromeres, neuromeres, and ‘transversal bands’ of migration areas) and proliferative processes was studied. Embryos with early migration areas were treated with colchicine and in this way the proliferative activity was changed.
The number of cells in mitosis is increased by the colchicine and as a result of this the depth of the bulges is increased. The normally very shallow ventricular furrows come to resemble neuromeric furrows.
The occurrence of the bulges in normal development is therefore probably the result of local increases of proliferative activity, i.e. of the formation of proliferation centres. It is suggested that all three systems of transverse bulges (proneuromeres, neuromeres, and ‘transversal bands’) represent successive activations of transverse proliferation centres.
