GROWTH OF DENDRITIC TREES OF PURKINJE-CELLS IN CEREBELLUM OF RAT

The growth of Purkinje cell dendritic trees in the cerebellum of the rat was studied over the first 50 days of life, using the technique of network analysis and the Golgi-Cox impregnation method. A growth spurt occurred from the 10th-30th day post partum (pp) and involved the production of a massive number of branches of fairly constant length. Growth of the tree occurred firstly in the lateral domiain, so that by 15 days pp most trees were of adult width. Thereafter, increases in height occurred until 30 days pp. Associated with this change in direction of growth, from the mainly transverse to the vertical plane, was a deviation from the normal random pattern of branching of the tree, but this was reestablished when reorientation was complete, and growth in the vertical plane underway. The lengths of proximal segments increased once they had become established, but distal branches probably maintained a constant length. Changes in segment length, trichotomy, branching probability and growth cone morphology during development were discussed in relation to current concepts of dendritic growth.