The Ontogeny of Pit-1 Expression in the Human Fetal Pituitary Gland
Bibliographic record
Abstract
Pit-1 expression has been reported to be cell-type-specific in the adult human pituitary and in human pituitary adenomas. In contrast, studies of rodent fetal adenohypophysial development as well as mature rodent glands have indicated that the pit-1 mRNA is ubiquitously expressed and the protein is under translational control. To determine the ontogeny and localization of Pit-1 expression in the human fetus, we examined fetal pituitaries (n = 23) at various stages of gestation from 6 weeks to term using in situ hybridization (ISH) for pit-1 mRNA, immunohistochemical localization of Pit-1 protein, and combined ISH for pit-1 mRNA with immunohistochemistry for pituitary hormones. At 6 and 7 weeks of gestation, the cells surrounding both limbs of Rathke's cleft showed a moderate specific signal for pit-1 mRNA. At 7 weeks, only a few cells were immunoreactive for ACTH and there was no definite colocalization of that hormone with pit-1 mRNA. At 8 and 9 weeks of gestation, there was definite preferential expression of pit-1 mRNA in cells containing growth hormone (GH) but not ACTH, as well as in cells with no detectable hormone immunopositivity. At midgestation and after, there was clear correlation between pit-1 mRNA expression and hormone content; cells with GH, prolactin and/or thyrotropin immunoreactivity had abundant pit-1 mRNA, whereas those containing ACTH, FSH or LH were negative for pit-1 mRNA by ISH and its protein by immunohistochemistry. The signal for pit-1 mRNA was stronger in intensity and present in more cells in fetal than in adult adenohypophyses. The ontogeny of pit-1 mRNA expression indicates that it precedes the onset of pituitary hormone detection. Its abundance in the human pituitary early in gestation may reflect its role in cytodifferentiation and cell proliferation. The correlation between pit-1 mRNA detection and Pit-1 protein localization is consistent with a cell-type-specific pretranslational regulatory mechanism for Pit-1 expression in the developing human adenohypophysis.
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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".