Relationship between NMJ size and terminal Schwann cell morphology. Correlation analyses from both mouse (upper panels) and human (lower panels) NMJs. A significant, albeit modest, correlation was observed between NMJ size (AChR area) and tSC number in both mice (Ai) and humans (Bi). However, a stronger correlation was present between NMJ size and tSC area in both species (Aii and Bii). Also, an increase in AChR area was associated with a reduction in tSCs cytoplasmic extension (Aiii and Biii). Each data point represents a single NMJ and its tSCs (n = 126 mouse NMJs; n = 151 human NMJs). Pearson and Spearman correlation coefficients (r) for parametric and non-parametric variables, respectively. **P ≤ 0.01; ****P ≤ 0.0001.