Dendrites are usually equipped with thin, narrow, 1-5 micrometer long "dendrite spines".
The number of dendrite tags varies between different neuron types from less than 1,000 to more than 300,000. Dendrite tags are extremely important points of contact between neurons and are considered to be involved in the processes that lead to memory storage. Especially the excitatory synapses utilize the dendrite tags.
Nerve cells with high activity develop extra many dendritic tags. Aging neurons and neurons with low or morbid activity gradually lose their dendritic tags.
Recent research has shown that a neuron has two types of dendrite tags,
a) more permanent tags with stable synaptic contacts and that "sit where they should hour in and hour out".
b) dynamic tags that form, move little, establish a rapidly transient synaptic connection, retreat and disappear without a trace ("kiss and run"); All in the space of half an hour. Distant and evasive as snail's eyes.