Histological analyses of the yak testis development at four different developmental stages. a Testes weight of 3, 5, 8 and 24 months old domestic yaks. b H&E staining of testes from 3, 5, 8, 24 months old yaks. Data are presented as mean ± SEM of at least four yaks in a. Different letter denotes significantly different at P < 0.05. Scale bar = 50 μm.