What is Keeping Estrogen Inside the Human Ovarian Follicle?
Bibliographic record
Abstract
Estrogen is the major female sex steroid and its main site of production is the granulosa cells in the ovarian follicle. In the serum, almost all of estrogen is bound, mainly to sex hormone binding globulin (SHBG) and albumin. The average concentration of estrogen in the follicular fluid is a thousand times higher than the serum while the concentration of its binding proteins is equal or lower. Despite previous publications, we have shown that granulosa cells do not secret SHBG. The objective of this study was to identify the mechanism(s) responsible for maintaining this huge gradient of estrogen inside the follicle. After REB approval, we took samples of follicular fluid from women undergoing oocyte retrieval as part of an in vitro fertilization treatment. The fluid was placed in a tube made of a dialysis membrane with pore size of 0.5-3 KD and placed in chambers containing solutions with increasing concentrations of albumin 0-8 gr/dl. Despite higher levels of albumin in the outer chamber compared to the follicular fluid and serum, no significant diffusion of estrogen was demonstrated from the follicular fluid to the outer chamber. However, after treatment with either heat or trypsin to destroy protein, most of estrogen had diffused from the follicular fluid suggesting the presence of a novel binding protein that is not albumin or SHBG, for estrogen in the follicular fluid. Mouse anti-estradiol IgG monoclonal antibodies that bind both free and bound estrogen were covalently linked to Dynabeads (Magnetic beads) and incubated with the follicular fluid. After the removal of all the non-bound protein with buffer elution, the beads were washed with a 200 mM estrogen solution. The fraction of the follicular fluid eluted with estrogen was run on an SDS Tris-Glycine 4-20% gel. All the bands that were visualized by silver staining were analyzed with mass spectrometry displaying five binding proteins that were captured by the anti-estrogen antibodies. The gradient of estrogen concentration between the follicle and the serum is maintained by the action of as yet unidentified estrogen binding proteins other than SHBG and albumin. (poster)
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".