Abstract: Transforming growth factor-β1（TGF-β1）plays important roles during testicular development and spermatogenesis，the main aim of the study is to determine the expression and localization of TGF-β1 in alpaca testis. The testes were obtained from alpacas at the age of 12- and 24-months（n=3）at the Scientific Research Base of Shanxi Agricultural University. The protein expression of TGF-β1 in alpaca testes was examined by Western blotting. The cellular localization and developmental changes were examined by immunohistochemistry SABC The immunostaining of TGF-β1 was present in leydig cells,sertoli cells,myoid cells and spermatogenic cells in the testis of alpacas at the age of 12- and 24-months，the optical density（OD）of TGF-β1 were respectively 0.730 5±0.011 5 and 0.562 6±0.012 2 in leydig cell；0.420 7±0.013 0 and 0.325 7±0.008 2 in sertoli cells；0.645 5±0.082 0 and 0.656 9±0.023 0 in myoid cells；0.457 9±0.009 2 and 0.374 3±0.015 8 in spermatogonia（P<0.01）. The positive immunoreactivity was located at the cytoplasm，not in the nucleus.No positive immunoreactivity was observed in the negative control. From the changes in pattern of localization of this peptide, we conclude that TGF-β1 is strictly regulated in leydig cells,sertoli cells and germ cells.It suggests that TGF-β1 involves in the regulation of spermatogenesis，which provides direct evidences for TGF-β1 action in the alpaca testis during postnatal development and spermatogenesis.

Key words: alpaca, testis, TGF-β1, Western blotting, SABC