Project Summary: Somatic cell nuclear transfer (SCNT) replaces haploid meiotic chromosomes in metaphase (MII)-arrested oocytes with diploid interphase chromatin from somatic cells. Such SCNT oocytes are diploid and are not suitable for fertilization due to triploidy. However, our preliminary studies indicate that SCNT oocytes are capable of forming premature meiotic spindles consisting of paired single-chromatid chromosomes and subsequent activation or fertilization can induce segregation of somatic chromosomes into a pseudo polar body. Our research will determine if somatic homolog pairing and recombination in mouse SCNT oocytes can be induced by DNA double strand breaks and develop future therapeutic approaches for infertility treatments.