Use of superovulated mice as embryo donors for ES cell injection chimeras.

We examined whether superovulation can be used to improve the efficiency of donor embryo collection in embryonic stem cell injection chimera experiments. Superovulation of prepuberal C57BL/6 mice was compared with spontaneous ovulation of mature mice with respect to production and survival of blastocysts. Our results indicate that, compared with spontaneous ovulation, superovulation results in an increased number of blastocysts per female with no difference in viability when transferred to outbred Swiss Webster foster mothers. The advantage of using superovulated females, in terms of maintaining smaller numbers of both females and stud males, is discussed.