Fig. 3. The A11^13hd allele provided near normal function in kidney development. (A) Gross appearances of wild type, A11^-/- D11^-/- and A11^13hd/- D11^-/- kidneys. The A11^-/- D11^-/- kidneys shown are among the least affected, coming from one of the two mice that survived to P30. One kidney was severely reduced in size, with the other more normal. The A11^13hd/- D11^-/- kidneys appeared grossly normal except for a reproducible indentation on the left kidney (arrow). (B) Kidney histology. Top and middle panels: the A11^13hd/- D11^-/- kidneys appeared relatively normal compared with the A11^-/- D11^-/- kidneys, which showed many occluded proximal tubule (P) lumens (long arrows) and severely dilated distal (D) tubules (arrowheads). Short arrows point to glomeruli. Bottom panels: the medulla layer of both the A11^-/- D11^-/- kidney and the A11^13hd/- D11^-/- kidney (not shown) was severely reduced in size and disrupted by cysts (asterisk) when compared with the wild type. C, cortex; M, medulla.