Mouse care and experimental procedures were approved by the Animal Care and Use Committee of Kindai University (Application number: KAAT-22-001). All animal experiments were performed in accordance with the Guide for the Care and Use of Laboratory Animals. Mice were maintained on a 12:12 dark: light cycle at a constant temperature of 2223C and euthanised with cervical dislocation immediately before oocyte collection. Muscle tissues of a female Asian elephant ( Elephas maximus ), named Haruko, were collected from a carcass at necropsy at Osaka Municipal Tennoji Zoological Gardens, and frozen until use. The animal welfare and ethics were in accordance with guidelines adopted by the Japanese Association of Zoos and Aquariums.