Abstract

Electron micrographs of sections of mouse neocortical layer IV, cut tangential to the pial surface, show the detailed organization of neuronal groups or 'barrels', which are related functionally to single facial vibrissae. Cortical barrels comprise 'sides' of stellate and small pyramidal neurons, groups of myelinated axons, and apical dendrites. The 'cores' comprise a neuropil of thalamic afferents, sparse neurons, converging basal dendrites of pyramidal cells and stellate cell dendrites. Some neurons of the 'sides' are attached through puncta adherentia.