Ependymal Cells are a Heterogeneous Population in the Spinal Cord of the Leopard Gecko
Bibliographic record
Abstract
The leopard gecko ( Eublepharis macularius ) is an emerging model for the study of spinal cord regeneration. As for many lizards, leopard geckos are able to self‐detach their tails (to escape predation) and then spontaneously regenerate a replacement. The regenerate tail is characterized by a centrally positioned spinal cord with a relatively simple morphology: a layer of ependymal cells surrounded by nerve tracts. We hypothesize that ependymal cells in the spinal cord are a heterogenous population. Prior to injury, virtually all ependymal cells of the original (uninjured) spinal cord express the neural stem/progenitor cell (NSPC) marker Sox2, and a subset of these cells also express the astrocyte marker glial fibrillary acid protein (GFAP). Neurons of the grey matter, but not ependymal cells, co‐express the neuronal markers HuCD and NeuN. During regeneration, ependymal cells remain Sox2 + and begin to express additional NSPC markers including Musashi‐1, βIII‐Tubulin and Sox9. Interestingly, a subset of ependymal cells in both the original tail stump and the newly formed regenerate spinal cord begin expressing HuCD, a protein otherwise characteristic of neuronal differentiation. These cells are negative for NeuN (a marker of neuronal nuclei) and are positionally restricted to locations bordering the central canal. A second subset of ependymal cells within the regenerating spinal cord begin to express GFAP and Vimentin but not HuCD. Our results suggest that there are at least three distinct populations of ependymal cells present during regeneration. The majority of ependymal cells are HuCD/GFAP − and display a dynamic NSPC profile following injury (Musashi‐1 + / βIII‐Tubulin + / Sox9 + ). Two other populations are less widespread. HuCD + /GFAP − /NeuN − cells may represent a population of neuronal‐like central canal contacting cells, while HuCD − /GFAP + /Vimentin + cells appear to be ependymo‐radial glia. This complex assemblage of cells may explain the remarkable regenerative abilities of the spinal cord in this species. Support or Funding Information Natural Sciences and Engineering Research Council of Canada, Discovery Grant (400358)
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".