Male Germ Line Stem Cells Have an Altered Potential to Proliferate and Differentiate During Postnatal Development in Mice1
Bibliographic record
Abstract
Spermatogonial stem cells (SSCs) continuously support spermatogenesis after puberty. However, accumulating evidence suggests that SSCs differ functionally during postnatal development. For example, mutant mice exist in which SSCs support spermatogenesis in the first wave after birth but cease to do so thereafter, resulting in infertility in adults. Studies using a retroviral vector have shown that the vector transduces pup SSCs more efficiently than adult SSCs, which suggests that pup SSCs divide more frequently. Thus, it is hypothesized that the SSCs in pup and adult testes have different characteristics. As an approach to testing this hypothesis in the present study, we investigated the proliferation kinetics of pup SSCs (6-9 days old) and their self-renewal/differentiation patterns for the first 2 mo after transplantation, and compared them to those of adult SSCs. Using serial transplantation, we found that the number of pup SSCs declined over the first week after transplantation. Thereafter, it increased ~4-fold by 1 mo and ~9-fold by 2 mo after transplantation, which indicates that pup SSCs continuously proliferate from 1 wk to 2 mo after transplantation. Compared to the proliferation of SSCs derived from adult intact testes, that of pup SSCs was lower at 1 mo but similar at 2 mo, indicating the delayed proliferation of pup SSCs. However, the pup SSCs regenerated spermatogenic colonies at 1 mo that were similar in length to those of SSCs from adult intact testes. Therefore, these results suggest that some functional differences exist in SSCs during postnatal development, and that these differences may affect the abilities of SSCs to self-renew and differentiate.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".