Embryonic and fetal rat myoblasts form different muscle fiber types in an ectopic in vivo environment
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Limb muscle development is characterized by the migration of muscle precursor cells from the somite followed by myoblast differentiation and the maturation of myotubes into distinct muscle fiber types. Previous in vitro experiments have suggested that rat limb myoblasts are composed of at least two distinct myoblast subpopulations that appear in the developing hindlimb at different developmental stages. These embryonic and fetal myoblast subpopulations are believed to generate primary and secondary myotubes, respectively. To test this hypothesis, cells obtained from embryonic day 14 (ED 14) and ED 20 rat hindlimbs were analyzed for myosin heavy chain expression after long-term differentiation in adult rat brains. Fetal myoblasts from ED 20 hindlimbs produced muscle fibers with a phenotype similar to that seen in tissue culture--predominantly fast myosin with a small proportion also coexpressing slow myosin. However, injection sites populated by embryonic myoblasts from ED 14 hindlimbs produced a different phenotype from that previously reported in culture, with fibers expressing an entire array of myosin isoforms. In addition, a subpopulation of fibers expressing exclusively slow myosin was found only in the embryonic injection sites. Our results support the existence of at least three myogenic subpopulations in early rat limb buds with only one exhibiting the capability to differentiate in vitro. These findings are consistent with a model of muscle fiber type development in which the fiber type potential of myoblast populations is established before differentiation into myotubes. This process establishes myogenic subpopulations that have restricted adaptive ranges regulated by both intrinsic and extrinsic factors.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 it