Figure 4.

Histological analysis of lung and skin tissues. Hematoxylin and eosin-stained sections of the skin and lung of 6-wk-old wild-type, Fgf23^−/−, klotho^−/−, and Fgf23^−/−/klotho^−/− (DKO) mice. Note that compared to wild-type mice, a marked expansion of alveolar spaces is found in Fgf23^−/−/klotho^−/− mice. Such pulmonary emphysematous changes are also noted in Fgf23^−/− and klotho^−/− mice. Compared to wild-type mice, a marked atrophy of the skin in Fgf23^−/−/klotho^−/− mice is apparent. The subcutaneous fat tissue layer (arrows) in the wild-type skin is mostly absent in the homozygous mutant mice, either in the single Fgf23^−/− and klotho^−/− mice or in the Fgf23^−/−/klotho^−/− double mutant mice (lung and skin, ×10).