FB2026_03 , released September 17, 2026
CV Term Report
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Term perineurial glial sheath ID (Ontology) FBbt:00007089 (Fly Anatomy)
Definition The outermost cellular layer of the nervous system, probably of mesodermal origin (Hartenstein and Jan, 1992). This layer consists of glial cells, which participate in nutrient uptake and establish a first diffusion barrier (Limmer et al., 2014).[ FlyBase:FBrf0057603 FlyBase:FBrf0058936 FlyBase:FBrf0226917 ]
Also Known As"apical glial cell" ; "perineural sheath" ; "perineurial sheath"
CommentEvidence of mesodermal origin comes from the observation that embryos lacking mesoderm lack this cell layer and the overlying neural lamella (Edwards et al., 1993).
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VFB:FBbt_00007089
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 perineurial glial sheath (all annotations which use CV term, excluding "NOT" statements)
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nervous system
 |__perineurium__________
multi-tissue structure   |
 |__perineurium__________|
multicellular structure  |
 |__portion of tissue____|
                         perineurial glial sheath  143 rec.
                          |__perineurial glial cell 142 rec.
                              |__adult perineurial glial cell(+) 70 rec.
                              |__CNS perineurial glial cell(+) 73 rec.
                              |__embryonic/larval perineurial glial cell(+) 56 rec.
                              |__PNS perineurial glial cell(+) 26 rec.
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Is a portion of tissue
Part of perineurium
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VFB:FBbt_00007089