On the structure of IIIab-pyramidal cells in the human isocortex. A Golgi and electron microscopical study with special emphasis on the proximal axon segment.
In Golgi preparations of the adult human frontal cortex the IIIab-pyramidal cells show an apical dendrite with numerous side branches and several bifurcating basal dendrites. The dendrites are covered with numerous stalked spines. The axon takes a descending course giving rise to several collaterals. Ultrastructurally the proximal axon segment, i.e. the axon hillock and the initial segment, corresponds in a large degree to descriptions given for that of animals, including the tripartite substructure of the dense undercoating of the axolemma. In the human IIIab-pyramidal cells along the proximal part of the initial segment the undercoating displays gaps not only at the known sites but also opposite astroglial processes. The IIIab-pyramidal cells of the human isocortex require particular interest because they show almost exclusively a recently reported, age-related alteration of their proximal axon segment.
D000328:Adult; D000368:Aged; D001369:Axons / Q000648:ultrastructure*; D003712:Dendrites / Q000648:ultrastructure; D005260:Female; D005625:Frontal Lobe / Q000166:cytology*; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009474:Neurons / Q000166:cytology; D013569:Synapses / Q000648:ultrastructure; D013702:Temporal Lobe / Q000166:cytology