Fig. 3

Wnt11 signaling is coupled to the development of the collecting duct and the kidney medullary tubular architecture. Adult WT and Wnt11 ^−/− kidneys were prepared, sectioned and processed for immunohistochemistry with the collecting duct (CD) marker Aquaporin 2 (AQP2), the PT and loop of Henle marker lectin LTL, and DAPI, depicting the nucleus. Periodic Acid Schiff (PAS) staining was used for the histological examination. a–d The control kidney architecture, with longitudinal medullary rays consisting of the collecting ducts (green line), is deregulated in the Wnt11 ^−/− mice (compare c, d with a, b). e–l Confocal microscopy images with phase contrast. Note the control morphology of the terminal papillary tubules and Bellini ducts (e, f) and the narrower cross-section of the Bellini ducts in the Wnt11 ^−/− papilla (compare g, h with e, f). The high power micrographs depict AQP2 accumulation on the luminal side of the terminal papillary tubules in the WT (i, j), whereas AQP2 is also present on the basolateral side of the Wnt11 ^−/− cells (k, l). The papilla epithelial cells at the tip region have adopted an appearance similar to squamous cells (compare k, l with i, j). a–h, i, k) NB. j, l Adult. Bars: a, c 500 μm; b, d, e, g 100 μm; f, h, j, l 50 μm; i, k 25 μm