Panel A  shows untreated rat liver sections, with normal liver architecture. Panel B, C, D shows DEN treated rat liver sections, with  Oil red-O staining. B, C, D are the Initiation, Promotion and Progression Stages of Hepatocarcinogenesis. In untreated liver section (Panel A) it is negative staining but the staining is positive in Panel B (Initiation), C (Promotion) and D (Progression) and it is more in Promotion stage (Panel C) as the lipogenic molecules are more active in that stage.  a, b, c & d images are zoom out (3X) images of   panel A, B, C & D respectively.