Fig. 6. Differentiation defects in the kidney of Cp2l1^tra/tra mice. (A-K) In situ hybridization analysis of the kidney at birth. Expression of IC markers Atp6b1 (A) and Slc4a1 (B) was lost in Cp2l1^tra/tra mice. Expression of keratin 7 was lower in the whole CD of Cp2l1^tra/tra mice at E18 (C,E) and in the cortical CD (D,F; arrowheads) of newborn Cp2l1^tra/tra mice. By contrast, keratin 19 was more strongly expressed in the inner medullary CD of Cp2l1^tra/tra mice than Cp2l1^+/tra mice at birth (G). Expression of Gk-6 and Fxyd2c (orange) in DCT and CNT overlapped with that of Cp2l1 (lacZ staining; blue) (H). Expression of Gk-6 and Fxyd2c was not detected in Cp2l1^tra/tra mice at E18 (I,J). Expression of Clcnkb was also absent in the distal tubules of Cp2l1^tra/tra mice (K). (L,M) Quantification of mRNA expression by quantitative RT-PCR in isolated E14 kidney organ cultures (L) or in dissected kidneys at different developmental stages (M). The experiments were repeated at least twice. ^*P<0.005, P<0.05. (N) Comparison of gene expression between the kidney and the salivary glands. Analogous changes in gene expression were observed in these organs in Cp2l1^tra/tra mice. Changes are indicated with arrows, and a battery of genes commonly expressed in the developmental programs of these organs is shown in color. Scale bars: 200 µm in A,C,D,G,I,K; 100 µm in B,E,F,H,J.