Mice homozygous for the recessive Vac14ingls mutation are significantly smaller than their littermates, and their coat color is dilute with white underfur both dorsally and ventrally (Sweet 1991; Samples 2003). Most develop hydrocephalus with onset by one week of age. Homozygotes are weak and uncoordinated and have difficulty righting themselves. They fail to gain weight during the second week of life, and most die by three weeks of age. (Bronson et al. 2003) Length of survival appears to correlate with the severity of hydrocephalus, which varies from absent to severe; however, all homozygotes die by four weeks, whether or not they are hydrocephalic (Samples et al. 2003).
Hydrocephalus affects the lateral ventricles most severely; serial sections reveal an intact cerebral aqueduct. Diffuse astrocytic hypertrophy and hyperplasia are observed in brains and spinal cords of mutant mice. A few mutants develop status spongiosis, and a few exhibit gliosis alone. Astrocytes cultured from affected mice stop dividing within three weeks, but survive for up to 12 weeks. They do not develop into tumors when implanted into the brains of normal mice. (Bronson et al. 2003)
