“…Consequently, busulfan treatment is the most common method used to prepare recipients of spermatogonial stem cells transplantation [27,28] and to study spermatogonial stem cells kinetics and fertility recovery [29,30,31]. Busulfan can eliminate almost all endogenous germ cells in the recipient, creating an empty space in the spermatogonial stem cells niche; therefore, this drug has been used successfully to prepare recipients in mice [32,33], rats [34,35], pigs [36,37], dogs [38], hamsters [39], monkeys [40], and roosters [41].…”