Neuronal polyploidy and nuclear volumes in the cat central nervous system

Abstract

Nuclear DNA content has been measured cytophotometrically in neurons and glia of motor cortex, cerebellum, and spinal cord ventral horn of the cat. Betz cells, Purkinje cells and large neurons of ventral horn are tetraploid, while remaining neurons and glia in these areas are diploid, with the exception of an octaploid class in a small number of spinal cord neurons in 2 of 5 animals. The tetraploid neurons are the efferent neurons of their respective areas, and their nuclei are significantly larger than diploid nuclei. However, ploidy levels are not strictly proportional to nuclear volume in the cat central nervous system. Nuclear volumes vary among the different tetraploid neuronal types, Betz cell and tetraploid spinal cord nuclei having larger volumes than Purkinje cell nuclei. The nuclei of diploid neurons are significantly larger than those of diploid glial cells.