Abstract: Using the Western-blotting technique to detect the beta-casein protein from culture medium of bovine mammary epithelial cells(BMEC) in vitro, which can identify the normal physiological function of BMEC;Karyotype analysis identify the number and figure of Chromosome of BMEC cultured in vitro. The results show: containing betacasein protein in culture medium of bovine mammary epithelial cells in vitro shows that the mammary epithelial cells with normal physiological condition; the number of chromosomes in normal, it is 60, and the karyotype agreement with the mammalian chromosome map, shows that the cell lines in vitro culture conditions not transformation.

Key words: beta-casein protein; bovine mammary epithelial cells; chromosome