A Qualitative and Quantitative Electron Microscopic Study of the Neurons in the Primate Motor and Somatic Sensory Cortices

摘要: A study has been made of the neuronal somata in motor and somatic sensory cortices monkey. Pyramidal cells cortex are very similar to those described previously parietal cortical areas. The largest pyramidal area 4, Betz layer V, up 50 $\mu$ m transverse diameter. Although basically resembling smaller cells, nucleus a cell often complex indentation is relation overall size soma than that pyramid cytoplasm contains discrete clumps endoplasmic reticulum. As with other synapses on all symmetrical type. Previous descriptions stellate have receiving high density axosomatic both asymmetric Cells like this found termed here large cells. In addition their synapses, they abundant full organelles usually contain stacks Their dendrites similarly receive prominent moderately varicose shape. Large occur predominantly IV 3b but also commonly lower part III upper V. third class neuron type small These low some these sparse few organelles. They rounded or fusiform soma, frequently dark nucleus, no apical dendrite axon initial segments thin may be directed towards surface. Most II whereas more deeper layers cortex. quantitative was strip same width running through depth absolute numbers strips were as proportions each neuron, 72% cach being 21% 7% cortex, 23% 5% 3b. provided evidence form two distinct populations rather continuum.