156 INFLUENCE OF SERUM AND BSA ON BLASTOCYST DEVELOPMENT AND HATCHING IN IVF AND NUCLEAR TRANSFER BOVINE EMBRYOS
Bibliographic record
Abstract
Important differences exist between in vivo- and in vitro-produced bovine embryos. Studies have shown that various components in culture media affect embryo development, with serum producing some of the more detrimental effects. Efforts to develop a serum-free culture system have included looking at the effects of BSA, polyvinyl pyrrolidone and polyvinyl alcohol on embryo development. In this study, we compare serum and BSA during oocyte maturation and embryo culture of IVF and nuclear transfer (NT) embryos. Experiment A: Oocytes were aspirated from follicles and matured in either collection medium (Hams F-10 + 2% steer serum (SS); F-10) or in follicular fluid alone (FF). They were subjected to IVM-IVF-IVC as follows: 20–22 h maturation in synthetic oviductal fluid +8 mg mL-1 fatty acid-free BSA (SOF + BSA-FAF) supplemented with hormones, 18 h co-incubation with sperm in IVF-TALP, and culture for 9 days in SOF + BSA-FAF. Experiment B: Oocytes were randomly distributed for IVM-IVF-IVC into the following treatment groups: (i) IVM and IVC in SOF + 2% SS (SER), (ii) IVM in SOF + 2% SS and IVC in SOF + BSA-FAF (SER-FAF), (iii) IVM and IVC in SOF + BSA-FAF (FAF), and (iv) IVM and IVC in SOF + BSA-FrV (FrV). Experiment C: Oocytes were matured for 18 h in either SOF + 2% SS (SER) or SOF + BSA-FAF (FAF). Couplets were constructed with adult skin fibroblasts, exposed to a single pulse of 1.5 kV cm-1 for 40 s and activated using ionomycin and cycloheximide. Embryos were cultured in SOF + BSA-FAF. Three replicates with 100–120 oocytes per treatment group were carried out. Results: Cleavage rates were similar among all treatments in experiments A and B. No differences were observed between oocytes collected in F-10 or FF indicating that short-term exposure to serum does not have long-term effects on embryo development. Although a higher number of blastocysts was observed in the SER group on Day 6 (3.2% v. <0.5%; P < 0.05), no differences were seen in blastocyst development among the IVF treatment groups from Day 8 onwards (SER: 29.7%, SER-FAF: 21.1%, FAF: 20.4%, FrV: 19.9%). However, hatching rates on Days 8 and 9 were significantly greater (P < 0.05) in groups with serum, with the exception of FAF on Day 9 (SER: 31.1%, 57.2%; SER-FAF: 29.4%, 50.6%; FAF: 23.1%, 46.4%; FrV: 18.5%, 34.2%). In the NT treatment groups, the presence of serum during IVM resulted in a higher proportion of MII oocytes at 18 h, better oocyte quality for manipulation, and increased blastocyst development and hatching rates (SER: 31.4%, 18.2%; FAF: 21.7%, 4.8%). These results indicate that both serum and fatty acid-free BSA provide comparable embryo development during IVF. However, development in serum occurs at an accelerated rate as indicated by the shorter nuclear maturation times and blastocyst development on Day 6, which has been associated with adverse outcomes. Despite this, serum may provide the oocyte with factors that are important for membrane flexibility and repair, enabling greater survival after manipulation. Funding from NSERC and OMAFRA. Sperm provided by Gencor.
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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 | 0.001 |
| 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) | 0.001 | 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".