A glial cell that is part of the perineurium. This cell type has thin long bipolar cytoplasmic processes, pinocytotic vesicles, fragments of external lamina and/or external lamina-like material, attachment plaques, and desmosome-like junctions. Perineurial cells historically have been referred to as fibroblasts because of shape; however, unlike fibroblasts, a perineurial cell: does not have a compact nucleus and large endoplasmic reticulum; does have a double basement membrane opposed to a single basal lamina; is carefully joined to other perineurial cells by tight junctions into a single sheet as opposed to arranged in a large mass; and finally, can surround a small axon bundle at a nerve terminal whereas a fibroblast cannot. [ http://amigo.geneontology.org/amigo/term/GO:tfm NCIT:C41442 http://en.wikipedia.org/wiki/Perineurium https://orcid.org/0000-0001-7655-4833 http://www.ncbi.nlm.nih.gov/pubmed/25818566 ]