Effect of culture system on the yield and quality of bovine blastocysts asassessed by survival after vitrification

Citation
D. Rizos et al., Effect of culture system on the yield and quality of bovine blastocysts asassessed by survival after vitrification, THERIOGENOL, 56(1), 2001, pp. 1-16
Citations number
45
Categorie Soggetti
Veterinary Medicine/Animal Health","da verificare
Journal title
THERIOGENOLOGY
ISSN journal
0093691X → ACNP
Volume
56
Issue
1
Year of publication
2001
Pages
1 - 16
Database
ISI
SICI code
0093-691X(20010701)56:1<1:EOCSOT>2.0.ZU;2-9
Abstract
The aim of this study was to assess the effect of a bovine in vitro culture system on blastocyst yield and quality after vitrification. In Experiment 1, IVM/IVF zygotes were cultured in either synthetic oviduct fluid (SOF) in 5% CO2, 5% O-2, 90% N-2; Or TCM199-granulosa cells (TCM199-GCM) in 5% CO2 in air. In vivo blastocysts were used as a control. Culture in SOF resulted in a significantly higher blastocyst yield on both Day 7 (31.3 vs 13.2%, P < 0.001) and 8 (36.8 vs 23.7%, P < 0.001) than did culture in TCM199-GCM. After vitrification, survival at 72 h of in vivo blastocysts was significan tly higher than both in vitro groups, while significantly more blastocysts produced in TCM199-GCM survived compared to those produced in SOF (0, 43.5, 78.3 % for SOF, TCM199-GCM and in vivo, respectively P < 0.01). In Experim ent 2, SOF-GCM proved to be the best post-warming culture system of those t ested and was adopted as the post-warming medium for all subsequent experim ents. In Experiment 3, zygotes were cultured in SOF or SOF-GCM, in either 5 % CO2 in air, or 5% CO2, 5% O-2, 90% N-2. In agreement with Experiment 1, c ulture in SOF in 5% O-2 resulted in significantly more blastocysts at Day 7 (26.4 vs 17.3%, P < 0.01) and Day 8 (31.5 vs 23.2%, P < 0.01) than did cul ture in SOF-GCM. However, survival at 72 h post vitrification was significa ntly higher for SOF-GCM (44 vs 8.3%, P < 0.001). Increasing the O-2 concent ration to 20% significantly reduced the blastocyst yield from SOF (31.5 vs 17.3%, P < 0.001). In addition, the quality of blastocyst produced was redu ced in terms of survival post vitritication (8.3 vs 0%, P < 0.05). In contr ast, there was no difference in blastocyst yield (23.2 vs 25.2%) or surviva l (44.0 vs 36.9%) in SOF-GCM, irrespective of O-2 concentration. Experiment 4 examined the duration of exposure to GCM necessary to acquire improved b lastocyst quality. Zygotes were cultured in SOF; SOF until Day 3, followed by SOF-GCM for the remainder of the culture; SOF until Day 5, followed by S OF-GCM for the remainder of the culture; or SOF-GCM for the entire culture. Survival at 72 h post vitrification was significantly higher (P < 0.05) in Groups 2 (50.0%, 13/26) and 4 (55.3%, 26/47) than in Groups 1 (21.7%, 10/4 6) and 3 (10.8%, 4/37). In conclusion, culture system can affect blastocyst yield and quality and crytolerance is a useful indicator of blastocyst qua lity. (C) 2001 by Elsevier Science Inc.