part of attached to portion of tissue perineurial glial sheath perineurium subperineurial glial sheath barrier glial cell layer FBbt:00007091 Inner glial cell layer of the perineurium that is probably not derived from the mesoderm (Edwards et al., 1994). This layer form an ion permeability barrier, functionally similar to the endothelial cells of the mammalian blood-brain barrier (Limmer et al., 2014). VFB:FBbt_00007091 That the subperineurial glial cells do not derive from the mesoderm is suggested by Edwards et al. (1994), in which they show the presence of these cells in delta (FBgn0000463) mutant embryos. 'Blood-brain barrier' may refer to this (e.g. Morante et al., 2013) or the perineurium (e.g. Limmer et al., 2014), which includes this and the perineurial glial sheath. fly_anatomy.ontology blood-brain barrier sub-perineurial glial sheath