Gross analysis of hydin mutant mice. (a) 11 pups from one litter on P13. The genotype is indicated. Note the growth retardation of the hy3/hy3 mice. (b) hy3/hy3 mutants develop hydrocephalus, which causes a dome-shaped skull (arrowhead). +/+, wild-type littermate. (c) X-ray images of hemisections through the skulls of a hydrocephalic animal (mut, OVE459) and a wild-type (wt) littermate. Arrowhead indicates the large radio-translucent cavity in the brain. (d) Coronal brain sections from wild-type and mutant (OVE459) littermates. Arrowhead indicates dilated lateral ventricle.