A neuropil, also known as neuropile, is a layer between neuronal cell bodies in the gray matter of the brain and spinal cord. It is composed of a dense tangle of axon terminals, dendrites and glial cell processes. It is where synaptic connections are formed between branches of axons and dendrites.
A neuropil is a complicated spatial network comprising interconnected neuronal processes intermingled with astrocytic glia processes. Synaptic neuropil is the basic constituent of the gray matter of the brain and spinal cord. White matter, which is mostly composed of axons and glial cells, is generally not considered to be a part of the neuropil.