Figure 4

Nonuniform density of spines. The electron micrographs illustrate single sections through the shaft of similar caliber dendrites from the (A) control and (B) LTP conditions. The dendrite membrane (yellow) with SER (green), representative microtubules (MT, arrow), and polyribosomes (PR, arrow) are indicated in the dendritic shafts. The 3D reconstructions of dendrites (yellow) from (C) Control and (D) LTP conditions include PSD areas (red), polyribosomes (blue arrows and spheres), and SER (green). Regions of high and low spine densities occur in patches along the dendritic segments.