Fig. 3. Genetic markers reveal that the renal capsule in the Foxd1 null is aberrant. Arrowheads indicate the position of the capsule. ß-Gal⁺ cells populate the capsule of the heterozygote (A) and mutant (B). Raldh2 expression in the heterozygote (C) is at high levels in the capsule and the cortical stroma (cs) and is at lower levels in the mesenchyme of the nephrogenic zone. In the mutant (D), Raldh2 is undetectable in the capsule, though a low level of expression remains in the mesenchyme. Sfrp1 expression in wild-type (E) is at high levels in the capsule, but almost undetectable in the mutant (F). Normally (G), Pecam1 expression (brown cells) is localized to the interior of the kidney, away from the capsular stroma (blue cells), but is in high abundance in the capsule of the Foxd1 null (H). Reactivity with peanut agglutinin (PNA) normally is not detectable in the capsule (I), but there is ectopic reactivity in the Foxd1 null at this age (J). Scale bar: 100 µm for A-D; 150 µm for E-H; 200 µm for I,J.