42 DIFFUSION OF THE CRYOPROTECTANTS ETHYLENE GLYCOL AND GLYCEROL INTO DAY 9 TO 11 EQUINE EMBRYOS: PRELIMINARY RESULTS
Bibliographic record
Abstract
The impermeability of the capsule to cryoprotectants (CPA) has been blamed for poor cryosurvival of equine embryos. We hypothesised that ethylene glycol, with its lower molecular weight and higher permeability, would be preferred over glycerol for equine embryos. The purpose of this study was to determine concentrations of glycerol and ethylene glycol within equine blastocoele fluid of Day 9 to 11 equine embryos following 30 min of exposure to a 1.5 M solution. Fourteen grade 1 embryos were recovered from May through September, using standard transcervical lavage techniques. Day of ovulation (Day 0) was determined as first appearance of the corpus luteum by daily transrectal ultrasonography, following insemination and administration of an ovulatory induction agent (Chorulon, 2500 IU; Intervet, Canada). Embryos were graded, measured, and washed in holding media (emP3TM Partnar Animal Health, Ontario, Canada), blocked by age, and randomly assigned to either 1.5 M ethylene glycol in holding solution (EG; n = 7) or 1.5 M glycerol in holding solution (Gly; n = 7) each containing 1% dimethyl sulfone as the internal standard, for 30 min at room temperature. Following CPA exposure, embryos were moved to a sterile, dry dish, all fluid was removed with a micropipette, and the dish dried with fine tissue. The embryonic capsule was punctured, and aspirated blastocoele fluid was analysed for CPA concentration by gas chromatography using a CP-3800 gas chromatograph (Varian Canada Inc., Mississauga, Ontario, Canada). The CPA concentration was determined by comparing the internal standard count to the accumulated CPA in millimoles per liter by gas chromatograph. A two-sample Kolmogorov-Smirnov test for equality of distribution was used because data were not normally distributed. Post-hoc 2-way t-test with unequal variances was used to compare mean effective CPA concentration across treatments, with significance set at P = 0.05. Collected embryos ranged from 1470 µm to 9240 µm in diameter, but there was no difference in embryo size between groups (P = 0.59). Mean concentrations of EG from blastocoele fluid were significantly higher than Gly (71.58 ± 18.9 mmol L–1v. 50.71 ± 11.2 mmol L–1, respectively; P = 0.016). This represents 4.8 and 3.4% of available CPA, respectively. Mean EG concentrations by embryo age were not different (Day 9: 68.3 ± 23.1 mmol L–1; Day 10: 83.0 ± 15.4 mmol L–1; Day 11: 71.0 ± 21.9 mmol L–1; P = 0.75). Mean Gly concentrations by embryo age were not different (Day 9: 47.0 ± 12.7 mmol L–1; Day 10: 46.0 ± 7.1 mmol L–1; Day 11: 56.3 ± 13.6 mmol L–1; P = 0.35). The low concentrations of EG and Gly found in this preliminary study are in agreement with indirect evidence from other studies. Ethylene glycol reached higher concentrations inside the embryo than glycerol because of lower molecular weight and higher permeability. However, permeation appeared to be minimal for both agents despite exposure to solutions of high CPA molarity.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.003 |
| 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) | 0.000 | 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 teacher head, 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".