Figure 3.

CITED1 immunoperoxidase staining of human fetal kidney (A and B) and Wilms' tumors (C and D). (A) Original magnification, x100; (B) original magnification, x400. (A and B) As in the rat fetal kidney, CITED1 expression is restricted to the condensed metanephric mesenchyme (CM) immediately adjacent to and surrounding the UB. (B) The earliest epithelial structures of mesenchymal origin, pretubular aggregates (*), and renal vesicles (RV) again show the absence of CITED1 expression in the human fetal kidney. (C) CITED1 expression is intense in malignant blastema (Bl) but absent in stroma (St) (original magnification, x100). (D) The region of blastemal-to-epithelial transition in human Wilms' tumor also shows a gradient of CITED1 expression from intense in peripheral blastema to absent in central epithelia (Ep) (original magnification, x400).