Characterization of Spontaneous Chondrogenesis During Tail Regeneration of the Leopard Gecko ( <i>Eublepharis macularius</i> )
Bibliographic record
Abstract
Many lizards are capable of spontaneous tail regeneration following tail loss. Although the regenerate tail superficially resembles the original, it is not identical. One of the main differences is that a cartilaginous cone replaces the original bony vertebrae of the axial skeleton. Here we characterize spontaneous chondrogenesis during tail regeneration in the leopard gecko. Following tail loss, the first sign of regenerative outgrowth is the formation of a blastema, an aggregation of proliferating mesenchymal‐like cells localized at the site of tail loss. Cartilage regeneration begins within the blastema 8–14 days post‐injury. Presumptive cartilage first appears as a glycosaminoglycan (GAG) and type II collagen (Col2) positive condensation that surrounds the newly regenerating spinal cord. With continued regenerative outgrowth, this condensation forms a hollow cone‐like structure. Presumptive cartilage cells express phosphorylated Smad2 (pSmad2), indicating activation of the canonical transforming growth factor beta (TGFβ) signalling pathway. Curiously, early pSmad2 expression is not matched by TGFβ1 or TGFβ3 expression, indicating that a different member of the TFGβ pathway is involved in early chondrogenesis. Furthermore, the transcription factor Sox9, often described as the master regulator of chondrogenesis, is not expressed until several days after the first appearance of Col2 and GAG in the newly forming tail. Chondrogenesis is complete within ~30 days, yielding a distinctly cell‐rich/matrix‐poor structure. Our findings indicate that regeneration‐mediated chondrogenesis in the lizard tail is not a simple recapitulation of embryonic cartilage development. Support or Funding Information Natural Sciences and Engineering Research Council (NSERC) 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".