BCL-6 expression in double-positive (CD4⁺, CD8⁺) cortical fetal thymocytes.

Three-color staining for BCL-6 (nuclear, pink-red), CD4 (cytoplasmic, brown), and CD8 (cytoplasmic, blue) of cortical thymocytes. Most cortical thymocytes expressing BCL-6 (nuclear, pink-red) are CD4⁺, CD8⁺ double-positive thymocytes (cytoplasm, muddy brown-blue). Insert, upper right corner, shows double staining for BCL-6 (nuclear, pink-red) and CD4 (cytoplasmic, brown) of cortical thymocytes; insert, lower right corner, shows double staining for BCL-6 (nuclear, pink-red) and CD8 (cytoplasmic, blue) (21 weeks gestational age). Original magnification × 1000.