A short-term hypotonic treatment for chromosome preparation of intact and zona-penetrated mouse embryos.

An air-drying method for chromosome preparation was improved for use in zona-penetrated mouse embryos. This method consisted of a sequence of short-term (1 to 3 min) hypotonic treatments, a two-step fixation process and slow air-drying under heavy moisture. The method is also applicable to intact embryos at the one-cell, morula, and blastocyst stages for chromosome analysis of embryos at each of these stages.