Expression of Vasa in pup and adult testes. (A) Detection of pup and adult testis morphology by H&E staining. The pup testes had smaller seminiferous tubules than the adult testes. The Vasa protein was expressed in cytoplasm of both pup and adult testes. Scale bar = 100 µm. (B) Analysis of Vasa gene expression using qRT-PCR. The Vasa gene was highly expressed in adult testicular cells (ATCs) compared with cultured spermatogonial stem cells (SSCs) and pup testicular cells (PTCs). These data were normalized by Gapdh, and the error bars represent ± SEM for three independent replicates. Different letters are statistically significant (p < 0.05).