Comparative Aspects of Placental Development.
Bibliographic record
Abstract
The placenta is composed of several different trophoblast cell subtypes that have been defined histologically with distinct anatomical locations, ultrastructural features and physiological functions ranging from nutrient transport to endocrine. The placenta is well known for its production of diverse hormones and growth factors and yet there is wide species variation in the types of hormones that are produced. Indeed there are several examples of large families of placental-specific hormone genes that have evolved independently in different species. For example, the IFN-tau genes have evolved from type I interferons and yet are present only in ruminant species. Rodents, by contrast, have a huge family of prolactin-related genes and primates have an expansion of growth hormone-related genes. We have tried to address the functional significance of such large placental-specific genes limited to a few species using detailed in micegene expression and gene knockout analysis. As a first case, we have performed detailed temporal and spatial gene expression analysis, using northern blotting and detailed in situ hybridization analysis, in the mouse placenta for the 24 genes in the Prolactin-like protein (PLP)/placental lactogen (PL) gene family which sits in a 1 Mb base of chromosome 13. As a group, the genes appear to be exclusively expressed in the placenta and yet, while there is some overlap of some genes, there are at least 14 different patterns of gene expression. There is no obvious correlation between gene expression and position in the gene locus. Surprisingly also, even close paralogues that are the most evolutionarily related often do not have identical expression. Bioinformatic analysis of promoter regions from genes with common subtype expression patterns can identify conserved regulatory elements that may direct trophoblast subtype-specific gene expression. These data suggest that the PLP/PL genes each have unique functions and that the various trophoblast cell subtypes have different physiological roles. These data raise questions about how the physiology of pregnancy is regulated in those species that do not have these placental hormones.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.017 | 0.004 |
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".