The pyramidal cells of Betz within the cingulate and precentral gigantopyramidal field in the human brain. A Golgi and pigmentarchitectonic study.

It can be demonstrated with the aid of Golgi-, Nissl-, and pigment preparations that the Betz cells represent a homogeneous class of giant cells within the human brain, which can readily be distinguished from other large pyramids by their densely aggregated lipofuscin deposits. In addition to the primary motor field (4, Brodmann), there exists only a small area on the medial surface of the hemisphere in front of the central sulcus which also contains large Betz pyramids in layer Vb. This recently discovered sulcus (Braak, 1976b). Compared with the Betz cells of the primary motor field (4, Brodmann), those of the cingulate area display numerous primitive traits. A small number of short basal dendrites springs off from the cell body. The apical dendrite forks in a short distance from the perikaryon repeatedly but issues only few side branches. A spine-free proximal dendritic segment is poorly developed or lacking. Moreover, numerous spines are encountered along the surface of the soma. In view of their primitive features the large pyramids of the cingulate gigantopyramidal area are interpreted as the forerunners of the precentral Betz pyramids.