3.4. Immunohistochemical analysis
The distribution of α-TTP in sheep liver is shown in Fig. 4A. Immunochemical staining tests showed that α-TTP staining (DAB, brownish color) was mainly cytosolic (Fig. 4A). A central venule of a hepatic lobule with marked positive staining in the hepatocytes is clearly visible while the region bordering the hepatic venule remained unstained. Fig. 4B shows the corresponding negative control with no α-TTP staining of hepatocytes when the primary antibody was omitted. Furthermore, all the thirty-five sheep liver tissue sections were stained and immunohistochemical analysis was used to determine the sheep α-TTP expression levels in response to different vitamin E supplementation levels. The result of immunohistochemistry revealed that the differences of the α-TTP protein levels between the groups were not significant (PN0.05) (Fig. 4C).