Abstract
Nonsurgical transfer and survival of frozen-thawed bovine embryos by one step straw method using sucrose
Exp 1. Bovine embryos were classified microscopically as A (Excellent), B (Good), C (Poor) ac-cording to the standard of GARY et al.2) Glycerol was added to the culture medium at room tempera-ture in three steps of 10 minutes each (3%, 6%, 10% respectively). After equilibration, the 0.25 ml straws were filled with three compartments, each separated by small air bubbles. The embryo was placed in the middle compartment containing PBS and 10% glycerol as cryoprotectant. The upper and lower compartments contained 0.3 mole or 0.6 mole sucrose solution in water supplemented with 20% bovine serum.
Then, the upper air bubble was removed by giving light pat to the straw by the finger and the upper and middle compartments were mixed. Then the straw was kept at 38C for ten minutes, meanwhile the lower compartment kept unmixed.
Ten minutes later the embryos in the straw were cultured for 24 to 72 h with Ham's F-10 +20% BS. All embryos classified as A and B were developed into blastocyst or hatched blastocyst after being mixed with 0.3 mole sucrose solution (10/10 and 2/2 respectively) or 0.6 mole sucrose solution (2/2 and 3/3 respectively).
Exp 2. After 1 to 300 day of preservation at -96C, the contents were thawed at 38 C and mixed by same method as Exp 1. Ten minutes later the embryos in the straw were cultured for 24 to 72 h with Ham's F-10+20% BS. A higher survival rate was obtained in the A class embryos (95% and 100% respectively) than that of the B class embryos (66.7% and 50.0% respectively) dilluted with 0.3 mole and 0.6 mole sucrose solutions.
Exp 3. The mean conception rates were 58.6% for Holstein recipients and 33.3% for Japanease black recipients.
