Figure 2.

Dendritic spines exhibit different types of morphological rearrangements. (a) A dendritic filopodium (arrow) appears and disappears (P). (b) Amorphous changes in the spine head (“morphing;” P). (c) Elongation of a spine (C). (d) Emergence of a filopodium (arrow) from a spine head (P). (e) Transient “touching” of neighboring spines (C). (f) Merging of split spine heads (P). (g) Length measurements of a transient dendritic spine, (h) a spine that elongates and retracts, and (i) a spine that elongates and remains elongated. Cellular origin of spines is denoted by: P, Purkinje; C, cortical pyramidal cells. Bar = 2 μm.