a. Ex vivo spinal cord slice culture model in which slices were cultured for 7 days, followed by 3 days in the presence of NMO-IgG (purified IgG from NMO serum) and human complement, without or with blocking antibody (rAbmut). Immunostaining shown for AQP4, GFAP and myelin. Controls include non-NMO IgG, NMO-IgG or rAbmut alone, rAbmut with complement, and slice cultures from AQP4 null mice. b. NMO lesion scores (see Methods) (S.E.M., n=4−5, * P < 0.001).