Role of chondrogenic tissue in programmed cell death and BMP expression in chick limb buds
Bibliographic record
Abstract
In the developing chick leg bud, massive programmed cell death occurs in the interdigital region. Previously, we reported the inhibition of cell death by separation of the interdigital region from neighboring digit cartilage. In this study, we examined the relationship between cell death and cartilaginous tissue in vitro. First, cell fate was observed with DiI that was used to examine cell movement in the distal tip of leg bud. Labeled cells in the prospective digital region were distributed only in the distal region as a narrow band, while cells in the prospective interdigital region expanded widely in the interdigit. In coculture of monolayer cells and a cell pellet tending to differentiate into cartilage, monolayer cells migrated into the cell pellet. These results suggested that digit cartilage tends to recruit neighboring cells into the cartilage during limb development. Next, we observed the relationship between cell death and chondrogenesis in monolayer culture. Apoptotic cell death that could be detected by TUNEL occurred in regions between cartilaginous nodules in mesenchymal cell culture. More apoptotic cell death was detected in the cell culture of leg bud mesenchyme of stage 25/26 than that of leg bud mesenchyme of stage 22 or that of stage 28. The most developed cartilaginous nodules were observed in the cell culture of stage 25/26. Finally, we observed Bmp expression in vitro and in vivo. Bmp-2, Bmp-4 and Bmp-7 were detected around the cartilage nodules. When the interdigit was separated from neighboring digit cartilage, Bmp-4 expression disappeared near the cut region but remained near the digit cartilage. This correlation between cell death and cartilaginous region suggests that cartilage tissue can induce apoptotic cell death in the developing chick limb bud due to cell migration accompanying chondrogenesis and Bmp expression.
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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 | 0.000 | 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) | 0.000 | 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".