Sperm penetration at the maturing metaphase I stage can trigger oocyte activation in a mouse model
Bibliographic record
Abstract
RESEARCH QUESTION: Can spermatozoa penetrate maturing metaphase I (MI) oocytes, and render subsequent development following conventional IVF in a mouse model? DESIGN: ICR mice were used in this study. Metaphase II (MII) cumulus-oocyte complexes (COC) harvested 15 h after injection of human chorionic gonadotrophin (HCG) were used for IVF as the control group (Group 1). In the treatment group (Group 2), maturing MI COC harvested 7 h after HCG injection were used for IVF. Fertilization, pronuclear formation, cleavage, blastocyst formation, DNA methylation status, chromosome number and live birth rates were used to evaluate the developmental dynamics and competency of maturing MI oocytes following conventional IVF. RESULTS: Maturing MI COC were fertilized using conventional IVF, and sperm penetration at MI-telophase I triggered oocyte activation. Most embryos resulting from fertilized MI oocytes developed to blastocyst stage during preimplantation development, albeit a substantial proportion of them were triploids due to the absence of the second meiotic division. Some of the embryos derived from fertilization of maturing oocytes were able to implant and gave rise to full-term development. CONCLUSION: Maturing MI COC from follicles before ovulation could be used for mouse IVF, and fertilized MI oocytes had high potential for development. Healthy offspring can be generated from maturing MI COC following conventional IVF. MI COC may represent a valuable source of 'usable' biomaterial in assisted reproduction. However, many embryos derived from MI COC via IVF have abnormal chromosome numbers in the mouse model. The implications of these findings for human IVF remain to be investigated.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 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".