Effect of lecithin on in vitro and in vivo survival of in vitro produced bovine blastocysts after cryopreservation.
The use of soybean lecithin in an glycerol-based solution for slow freezing of in vitro matured, fertilized and cultured (IVMFC) bovine embryos was examined. Embryos were developed in vitro in INRA Menezo's B2 medium supplemented with 10% fetal calf serum (FCS) on Vero cells monolayers. Day 7 blastocysts were frozen in a two-step protocol consisting of exposure to 5% glycerol and 9% glycerol containing 0.2 M sucrose in F1 medium + 20% FCS. Soybean lecithin was either added or not to the freezing solutions at a final concentration of 0.1% (w/v). In Experiment 1, blastocysts were equilibrated in cryoprotectant solutions without cooling. Cryoprotectant was diluted from embryos with 0.5 M and 0.2 M sucrose. The percentages of fully expanded and hatched blastocysts treated with or without lecithin after 24 and 48 h in culture were not significantly different (100 versus 100% and 93.3 versus 100%, respectively). In Experiment 2, the in vitro survival of frozen-thawed IVMFC blastocysts was compared when cryoprotectant solutions were either supplemented or not with lecithin. No significant effect of lecithin was found on the ability of frozen-thawed blastocysts to re-expand after 48 h in culture (65.6 and 54.2%, respectively). However, the post-thaw hatching rate of embryos cryopreserved in the presence of 0.1% lecithin was significantly higher after 72 h in culture (52 and 31.8%, respectively). In Experiment 3, the ability of frozen-thawed IVMFC blastocysts to establish pregnancy following single embryo transfer was determined. Transfers of 58 and 66 frozen-thawed embryos cryopreserved with or without lecithin resulted in 6 and 10 (10.3 and 15.1%, respectively) confirmed pregnancies at Day 60. Addition of lecithin to cryoprotectants did not improve the in vivo development rate of cryopreserved IVMFC bovine blastocysts.
Guyader-Joly
C
C
UNCEIA, UCEAR Laboratoire FIV, Chateauvillain, France.
Ponchon
S
S
Durand
M
M
Heyman
Y
Y
Renard
J P
JP
Ménézo
Y
Y
D000818:Animals; D001755:Blastocyst / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D002522:Chlorocebus aethiops; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro; D008297:Male; D010053:Ovary / Q000166:cytology; D010713:Phosphatidylcholines / Q000494:pharmacology*; D013025:Glycine max; D013395:Sucrose; D014709:Vero Cells
D003451:Cryoprotective Agents; D010713:Phosphatidylcholines; D013395:Sucrose