Vertex analysis of the growth of Purkinje cell dendritic fields of the mouse
Abstract
The purpose of this study was to quantify the growth of Purkinje cell dendritic fields in mice, so that changes with time in segment frequency, length and topology are defined. Our results show that changes in the Va/Vb ratio are consistent with the hypothesis that growth is by random terminal branching with the intrusion of 5-8% trichotomy and with inhibitory constraints operating in the lateral domains. The changing frequency distribution of vertex orders with time indicates that initially growth predominates over high orders as a front of growth ascends a narrow corridor physically defined by the margins of juxtaposed trees. Subsequent branching occurs over low order vertices as the boundaries of the tree stabilise. Path lengths increment uniformly over established equivalent orders, because all segment lengths are similar, but growing segments have smaller, more variable lengths. All segments elongate by terminal and interstitial growth.