Altered Dendrites in YFP-MeCP2 Mutant Mice Figure 3. Spine density is variably affected in different dendritic compartments in YFP+ MeCP2J mutant L5 pyramidal neurons. A–D) Spines were quantified in 20–30 mm segments in four dendritic compartments for WT and mutant YFP+ neurons. Scale bar (A) = 5 mm (all images). A) Apical tuft dendrites were sampled ,60 mm from the pial surface. B) Primary apical dendrites were imaged between 100–200 mm from the soma. C) Secondary apical dendrites originating in the same region as (B) were sampled beginning at the branch point from the primary apical dendrite. D) Basal dendrite spine counts were initiated following the first dendritic bifurcation. E) Spine density is reduced by 47.4% in the apical tuft and by 54.5% in secondary apical dendrites. doi:10.1371/journal.pone.0031896.g003 Discussion Morphological Analysis We analyzed the impact of the MeCP2J mutation on YFP+ L5 pyramidal cells and found two principal effects: 1) reduced branching and length in proximal basal and apical tuft dendrites, and 2) selective reductions in spine density limited to the apical tuft and secondary apical dendrites. These results contribute to a growing body of evidence showing that the effects of different MeCP2 mutations are highly sensitive to cellular context and cannot be readily generalized. The morphological differences observed in MeCP2 mutant neurons vary both across mutation types in the same cell population and within mutation types across different cell PLoS ONE | www.plosone.org 5 March 2012 | Volume 7 | Issue 3 | e31896