Fig. 6.

In situ hybridization analysis of CYP26A1, RBP4, β-actin, and α-smooth muscle actin (α-SMA) mRNA transcripts in the liver of adult rats. Glass slides containing liver sections of vitamin A-deficient and vitamin A-adequate rats orally treated with either oil as vehicle or all-trans-RA for 6 h (A) or sections of VA-adequate rat liver (B, C) were first prehybridized and then hybridized to either digoxigenin-labeled sense or antisense RNA riboprobe of CYP26A1 (A and B) or RBP4, β-actin, or α-SMA (C). After washing, the slides were incubated first with alkaline phosphatase conjugated anti-digoxigenin antibody and then with phosphatase synthetic substrate as described in materials and methods. The slides were washed and imaged under a digital microscope. In A, dashed circle surrounds a portal area where signal was more intense. In C, for β-actin, white arrow denotes signal around portal area and black arrow denotes signal scattered in what appear as stellate cells; for α-SMA, white arrows denote signal around portal areas and bile ducts. Scale bars: A, 100 μm; B and C, 50 μm.