The use of amniotic fluid and serum with propanediol in freezing of murine 2-cell embryos.

Human and mouse embryos have been cultured in amniotic fluid (AF). Human AF and human serum (HS) are used in the freeze-thaw of 2-cell mouse embryos. Two hundred seventy-five 2-cell embryos were collected into phosphate-buffered saline with 20% HS and 20% AF and into 100% HS and AF. The embryos were cooled with propanediol as cryoprotectant at a controlled rate. After thaw, they were cultured in T6 with 3 mg/ml bovine serum albumin. Blastocyst formation post-thaw was 56/79, 44/70, 51/61, and 56/79 of intact embryos from 20% HS, 20% AF, pure HS, and pure AF (NS). But blastocyst hatching was better from embryos frozen in pure HS (22/61, compared with 16/79 for 20% HS; P less than 0.05). Hence there is no advantage in using AF in freeze-thaw, but pure HS may be of use.