Term: class A neuron

Definition: The first and most common group (class A of Grossman et al. 1973) (Fig. 1) consists of cells which vary in soma diameter from 11 to 20 microns (mean = 14.0 microns). These cells have 4-8 primary dendrites, of roughly equal size, each of which branches between 6 and 12 microns from the soma to form 2-3 secondary dendrites. Secondary as well as tertiary dendrites (when present) possess irregularly spaced appendages which are either short and blunt in appearance, or appear as short, thin stalks with terminal swellings. These latter appendages were often seen at dendritic branch points, and resemble the grape-like clusters described on neurons of the cat LGN (Guillery 1966).