Striatal nuclear HTT aggregation is not reduced or delayed with loss of Msh3. Coronal striatal sections from wild-type (WT), zQ175, zQ175:Msh3+/− and zQ175:Msh3−/− at 3 and 6 months of age were immunohistochemically stained with the S830 antibody. A nuclear counterstain was not applied to these images, as this would mask the nuclear signal. (A) HTT aggregation was detectable by 3 months of age in the zQ175 mice and S830 immunostaining levels were comparable irrespective of Msh3 genotype. (B) Thresholding was applied to images to quantify levels of staining of S830 positive objects, average area of object, and the percentage of image covered. The Msh3 genotype had no impact on these three measures of S830 staining. (C) At 6 months of age, in addition to diffuse nuclear aggregation, nuclear inclusions were also prominent in many nuclei. (D and E) Thresholding was applied to quantify the number of (D) S830 positive objects and (E) inclusions. In each case, the number of objects, the average area of the objects and the percentage of an image covered by the S830 signal was determined. One-way ANOVA with Bonferroni correction. Error bars = standard error of the mean (SEM). n = 5/zQ175 genotype, n = 3 wild-type. Scale bar in large image = 10 μm, scale bar in inset = 5 μm. M = months.