Human Fetal Adenohypophysis
Bibliographic record
Abstract
The pituitary glands were removed from 63 human fetuses from 5 weeks of gestation to term and studied by electron microscopy and ultrastructural immunocytochemistry to document the development of cell differentiation and hormone production in the adenohypophysis. At 5 weeks of gestation, Rathke’s cleft was lined by columnar epithelium with abundant cytoplasmic glycogen and occasional secretory granules. By 6 weeks of gestation, cells resembling corticotrophs were identified; in 8-week-old fetuses, type I microfilaments were found in those cells. Well-differentiated somatotrophs were seen in adenohypophyses of 8- to 9-week-old fetuses. Although secretory granules were numerous, the Golgi complex was inconspicuous in early fetal glands. After 10 weeks of gestation, there was a change with morphologic evidence of active hormone secretion; large Golgi regions and sparsely granulated cells were found. Some somatotrophs at this stage contained aggregates of type II microfilaments which resembled the fibrous bodies of sparsely granulated somatotroph adenomas. Densely granulated mammosomatotrophs containing growth hormone and prolactin were identified at 12 weeks of gestation. Cells with characteristics of the glycoprotein hormone cell line were seen in pituitaries at 12 weeks of gestation; thyrotrophs and gonadotrophs were identified after 15 weeks. Typical lactotrophs were not recognized before 23 weeks, but were numerous in pituitaries of fetuses older than 35 weeks. This study documents for the first time the existence of a bihormonal mammosomatotroph in the human fetal pituitary and confirms that somatotrophs and lactotrophs, the two acidophil cell types, are embryologically related. Sparsely granulated somatotrophs appear after densely granulated somatotrophs at a time when fetal serum growth hormone reaches acromegalic levels, and it may be that the two cell types reflect differences in the hormonal milieu. The ultrastructural features of developing adenohypophysial cells resemble those of adenomas found in adult pituitaries, and fetal cytodifferentiation may help to clarify the significance of morphologic variants of adenomas.
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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) | 0.002 | 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".