Some types of synaptic specializations of dendrites.
(Adapted from Fiala and Harris, 1999.)

Pattern	Characteristics	Examples
Varicosity	An enlargment in a thinner dendrite associated with synaptic contacts	Retinal amacrine cells
Filopodium	A long, thin protrusion with a dense actin matrix and few internal organelles	Normally only seen during development
Simple Spine: Sessile	Synaptic protrusions without a neck constriction Stubby spine Crook thorn	Pyramidal cells of cortex Cerebellar dentate nucleus
Simple Spine: Pedunculated	Bulbous enlargement at tip Thin spine Mushroom spine Gemmule	Pyramidal cells of cortex Pyramidal cells of cortex Olfactory bulb granule cell
Branched Spine	Each branch has a unique presynaptic partner and each branch has the shape characteristics of a simple spine	CA1 pyramidal cells Granule cells of dentate gyrus Cerebellar Purkinje cells
Claw Ending	Synaptic protrusions at the tip of the dendrite associated with one or more glomeruli	Granule cells of cerebellar cortex and dorsal cochlear nucleus
Brush Ending	Spray of complex dendritic protrusions at the end of dendrite that extends into glomerulus and contains presynaptic elements	Unipolar brush cells of cerebellar cortex and dorsal cochlear nucleus
Thorny Excrescence	Densely lobed dendritic protrusion into a glomerulus	Proximal dendrites of CA3 pyramidal cells and dentate gyrus mossy cells
Racemose Appendage	Twig-like branched dendritic appendages that contain synaptic varicosities and bulbous tips	Inferior olive Relay cells of lateral geniculate nucleus
Coralline Excrescence	Dendritic varicosity extending numerous thin protrusions, velamentous expansions and tendrils	Cerebellar dentate nucleus Lateral vestibular nucleus