Dendritic spine

A dendritic spine is a mushroom-shaped bud or projection of a dendrite that forms the one half of a synapse, especially in neurons of the cortex. The dendrites of cortical neurons typically are densely covered with such spines, which enable a single cell to receive input from thousands of others. Spines are roughly equal in diameter to the dendrites from which they sprout, if not somewhat larger. As result, they are too small to see with a conventional microscope, but may be seen by confocal and electron microscopy.