Practice question

Mules are sterile interspecific hybrids from horse and donkey parents with 63 chromosomes preventing normal meiotic pairing, exemplifying hybrid sterility. Cloning a mule addressed whether sterile hybrids retain complete diploid genome capable of somatic nuclear reprogramming. In 2003, Idaho Gem, a mule foal, was produced by somatic cell nuclear transfer from fetal fibroblasts at University of Idaho, becoming first cloned equid and first cloned sterile animal. Success proved sterility due to germ cell meiosis failure not lack of genomic competence, opening conservation of endangered or sterile hybrids. Sheep Dolly illustrated fertile mammal cloning earlier.