Survival of bisected mouse embryos after exposure to pronase and medium free of calcium and magnesium

Abstract Pronase or acidified Tyrode's solution was used to digest the zona pellucida of mouse embryos and medium free of calcium (Ca) and magnesium (Mg) was used for decompaction prior to bisection. Exposure of 8- to 16-cell embryos to pronase (0.5% for 1.5 to 2.0 min) followed by decompaction (for 20 min) allowed a higher proportion of development of demi-embryos into blastocysts (47.7%) after overnight culture than did exposure to pronase alone (21.4%) or removal of the zona pellucida with Tyrode's solution (pH 2.0 or 2.5) followed by decompaction (18.0% and 18.8%). Bisected eight-cell embryos cultured overnight yielded no live young when transferred to females on Day 3 of pseudopregnancy. However, transfer of 196 bisected 16-cell embryos after treatment with pronase, decompaction, and overnight culture produced 20 live young (2 sets of twins and 16 singletons), a yield of 20.0% in pregnant mice and 10.2% overall.