PTvHC communicating HC and polycystic kidney disease in stumpy mutant mice. (A) Photographs of representative +fl and fl/fl mice (Upper) showing classic “domed head” of hydrocephalic fl/fl mice at P16. By P12, fl/fl mice consistently appear runted (Lower). (B) Whole brains isolated from +/fl and fl/fl mice (Left), and low-magnification photomicrographs of H&E-stained coronal brain sections (Right) showing pronounced venticulomegaly. (C) Nestin-cre-positive mice bearing one floxed allele (cre +, +/fl) were crossed with nestin-cre-negative –, +/fl mice, and all deficient offspring (cre +, fl/fl) manifested perinatal hydrocephaly. An additional 20/104 hydrocephalic cre +, fl/fl mice were identified from cre +, +/fl x cre−, fl/fl breedings. (D) Coronal H&E-stained sections show complete stenosis of the S. aq in fl/fl brains (Right). An enlarged 3v and thinner neocortex (nctx) are also observed in fl/fl brains (Right). (Scale bars, 100 μm.) (E) Motor function in wild-type (+/+, n = 9), +/fl (n = 10), and fl/fl mice (n = 6) was assayed by accelerating roto-rod, and data are represented as means ± SE of time to fall (latency, in seconds) for each of three consecutive trials. *, P < 0.001 for fl/fl vs. +/fl or +/+. (F) H&E-stained sections from +/fl or fl/fl P12 kidneys show evidence of polycystic kidney disease. High-magnification Insets are shown in the upper right corners. (Scale bars, 20 μm.)