Dendritic spine
A
dendritic spine is a mushroom-shaped bud that protrudes from a
dendrite and forms one half of a
synapse, especially in synapses of the
cortex. The dendrites of cortical
neurons typically are densely covered with such spines, which enable single cells to receive input from thousands of others. Spines in the human
brain are about one
micrometer in diameter, roughly the same as the dendrites from which they sprout, if not somewhat larger. As result, they are too small to see with a conventional microscope, but are visible by confocal and
electron microscopy. Most synapses in the human brain involve dendritic spines.