perineurium

Enclosed fascicle

Record the fascicle enclosed by the candidate sheath and the anatomical extent actually observed.

1. Which species, nerve, segment and fascicle does this perineurium belong to? provenance
2. What demonstrates that the candidate boundary encloses a fascicle rather than the entire nerve or an individual fiber? boundary

Sheath and compartment boundaries

Identify the perineurial tissue boundary separately from epineurium, endoneurium and isolated perineurial cells.

1. Where do the inner and outer perineurial surfaces lie in this preparation? boundary
2. Does the observation concern a native sheath, a fragment of it or cells identified as perineurial? definition

Lamellar geometry

Measure local sheath thickness and resolved layer count without assigning an unsupported normal range.

1. How many cellular lamellae are resolved at each sampled location? measurement
2. What is the sheath thickness, and how were oblique sections and tissue shrinkage addressed? measurement

Structural sealing evidence

Record observed cell junctions, basal laminae and matrix organization separately from conclusions about permeability.

1. Which cell contacts and associated basal laminae can the chosen method actually resolve? measurement
2. What evidence supports perineurial cell identity rather than identification from position alone? provenance
3. Which apparent gaps could result from sectioning, fixation or limited resolution? boundary

Probe-specific passage

Represent permeability as an observation for a named substance, exposure and direction rather than a universal sealed-or-open property.

1. Which substance was tested, at what concentration, for how long and in which direction across the sheath? measurement
2. Was passage measured quantitatively or inferred from tracer localization? measurement
3. What control excludes entry through exposed ends or preparation-induced breaches? boundary

Sheath versus vessel route

Require route-specific evidence before attributing endoneurial tracer entry to perineurium; these routes showed different permeability behavior in [a nerve-grafting experiment](https://pubmed.ncbi.nlm.nih.gov/537675/).

1. What distinguishes passage across the sheath from leakage through endoneurial vessels? boundary
2. Does the experiment measure perineurial function specifically or a combined nerve-barrier outcome? definition

Breach and deformation

Record the position and extent of sheath alteration while separating observation from its proposed cause.

1. Where is the sheath disrupted, separated or deformed, and over what measured extent? measurement
2. What evidence links the alteration to loading, injury or disease rather than specimen handling? provenance

Structural and functional recovery

Treat restored enclosure and restored permeability control as separate outcomes; compartment formation and persistent tracer permeability coexisted in [experimental nerve grafts](https://pubmed.ncbi.nlm.nih.gov/537675/).

1. What evidence shows continuity or lamellar reorganization at each observed time point? measurement
2. Was barrier function tested independently of the appearance of structural repair? measurement
3. Which species, injury model and follow-up interval limit application of this repair evidence? provenance

Assessment adequacy

Match imaging, section sampling and functional assays to the specific perineurial property under assessment.

1. Can this preparation resolve the lamellae, junctions or discontinuity relevant to the question? measurement
2. How much of the fascicular circumference and longitudinal extent was examined? measurement
3. What additional evidence is required before generalizing this observation to the intact sheath? action

Manipulation footprint

Specify whether an action remains outside the sheath, contacts it or breaches it, and how the resulting change would be assessed.

1. Would the proposed action contact, remove or cross the perineurium of an identified fascicle? boundary
2. What procedure-specific evidence and qualified judgment are required before proceeding? action
3. How would the location and extent of any resulting sheath disruption be documented? action

Check these first

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these check these first hold for the sense of perineurium this model covers, and on what evidence? provenance

Identifiers and schemes

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these identifiers and schemes hold for the sense of perineurium this model covers, and on what evidence? provenance

Real-world use

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these real-world use hold for the sense of perineurium this model covers, and on what evidence? provenance

Failure modes and hazards

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these failure modes and hazards hold for the sense of perineurium this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of perineurium this model covers, and on what evidence? provenance