The horse female X donkey male cross produces a mule; the reciprocal cross produces a hinny. These hybrids have 63 chromosomes and their mitochondria are of maternal origin. Both mules and hinnies are sterile, but mules have been successfully cloned. The procedure involved implanting a nucleus from a mule fetus into the enucleated egg from a horse. Therefore cloned mules also have horse mitochondria. See Chronology, 1974, Hutchison; Equus, donkey.
Subjects: Genetics and Genomics.