Each pair of panels shows the fluorescent image on the left and the corresponding DIC image on the right. CB, Cajal body; N, nucleolus. (A) Five B-snurposomes and a nucleolus stained with an antipeptide antibody against TFIIF (RAP74). (B) A Cajal body from the same preparation as A, printed at lower contrast. The Cajal body stains much more intensely than its associated B-snurposomes. (C) A Cajal body, nucleoli, and B-snurposomes stained with an antipeptide antibody against the 100-kDa subunit of the cleavage/polyadenylation specificity factor CPSF. The Cajal body stains intensely. (D) A Cajal body, three B-snurposomes, and a nucleolus stained with an antipeptide antibody against the 77-kDa subunit of the cleavage stimulation factor CstF. The Cajal body is the most intensely stained structure.