Loss of neurons from the spiral ganglion of the inner ear. Decalcified cochleae from mice of the indicated genotypes were incubated with alcian blue for selective staining of sulfatides, post-fixed with osmium tetroxide and embedded in paraffin. a: ASA+/+ CGT+/+ mouse (age 18 months). The neuronal perikarya are densely packed and intermingled with myelinated fibres of the cochlear nerve. Alcianophilic (sulfatide rich) structures are absent from the ganglion. b: ASA-/- CGT+/+ mouse (age 17 months). The neurons (N) contain alcianophilic material and are greatly reduced in number. The other cells which are heavily laden with alcianophilic material are macrophages (M) and Schwann cells (not labelled). c: ASA-/- CGT+/- mouse (age 17 months). The loss of neurons is less dramatic than in c, whereas the sulfatide storage in neurons and macrophages appears similar. Bar, 50 μm for all figures. d: Quantitative measurement. Number of spiral ganglion perikarya per test area measuring 120 μm × 120 μm. Age of the deficient mice 14–17 months. Values for wild-type mice at 10–18 months of age were taken from . The numbers of animals used for analysis (n) are given inside the columns. Error bars represent standard deviations of the mean values.**P ≤ 0.01 knock out against wild type by 1-way ANOVA.