Round spermatids from hybrid sterile mice can initiate normal embryo development.

Fertilization and embryo development following intracytoplasmic injection of round spermatids collected from hybrid sterile mice (BALB/c) were investigated. The rates of oocyte activation, blastocyst formation and development into live offspring were compared with those after intracytoplasmic injection of round spermatids from fertile mice (B6D2F1). The injection of oocytes with round spermatids from hybrid sterile or sterile males resulted in similar rates of normal fertilization and embryo development. The rates of development to term of 2-cell embryos were also similar, regardless of the origin of the round spermatids injected. This finding suggested that round spermatids from hybrid sterile mice have the ability to fertilize normally and to allow normal embryo development.