Fig. 9.5. Neuropil in layer 6 of the primary visual cortex in a 25 year old monkey. In the middle of the field is the profile of a swollen axon terminal that appears to be degenerating. The profile is identified as belonging to an axon terminal by the presence of a cluster of synaptic vesicles in the cytoplasm on one side of the profile. On the other side of the profile is a row of mitochondria and the rest of the cytoplasm is filled with what appear to be neurofilaments.
