Comparison Between the Densities of Neurons, Synapses and Axons

Abstract

The fact that 4 km of axons belonging to 9.2 x l0⁴ neurons allot more than 4 cm of axon to each neuron is surprising, especially since direct measurements on Golgi preparations have led to values less than half that figure. It must be noted, however, that the measurements in Braitenberg 1978 b which refer to pyramidal cells (the classification of cell types will be introduced in Chap. 15) do not consider the re-entrant axons of these cells. These may make considerable terminal arborizations which are only rarely stained by the Golgi procedure and if they are, are practically never seen in continuity with the other part of the axonal tree.