The number of Purkinje cells and inferior olivary neurones in the cat

Abstract It is generally assumed that (i) all neurones of the inferior olive send their axons to the cerebellum; (ii) the fibers from the olive end as climbing fibers; (iii) one climbing fiber establishes extensive synaptic contact with one Purkinje cell. From this it has been inferred that there is one inferior olivary neurone per Purkinje cell. The number of neurones in both inferior olives from four cats have been counted in histologic sections. The totals obtained are 145380, 127270, 126920 and 121360, respectively. In two of the cats the Purkinje cells were counted. The ratios of inferior olivary neurones to Purkinje cells were found to be 1 : 10 and 1 : 11, respectively.