Fig. 1.

Immunolocalization of AQP2, AQP1, and ClC-K in transverse section from rat inner medulla, located ∼400 μm below the outer medulla. Five primary clusters (outlined by white lines) make up a single secondary collecting duct (CD) cluster. Intercluster boundaries (white lines) are determined by Euclidean distance map technique; intracluster boundaries (red lines) are polygons drawn by eye. The combined area of the intercluster regions of the five primary clusters is 0.0235 mm² and the combined area of the intracluster regions is 0.0169 mm² (8). Black box outlines area shown in inset. Inset: arrow indicates nearest-neighbor distance between AQP1-positive descending thin limb (DTL) and CD. Scale bars, 100 μm; inset, 25 μm. Figure modified from Ref. 30.