Melanocytes within human skin have dendritic spine-like structures. (A) Serial section TEM of a melanocyte dendritic spine-like structure in intact neonatal foreskin. Melanocyte dendrite highlighted in purple: m, melanosome; k, keratinocyte; keratinocyte processes highlighted in green. See also Fig. S4 A. (B) Dendritic spine-like structures from reconstructed melanocytes in the 3D FIB-SEM model are similar in shape and (C) size (n = 19, from four cells) to those in culture. Orange bars represent the distribution range from co-cultured (in vitro) spines. (D) Pooled vesicles in keratinocyte adjacent to melanocyte stubby shaped dendritic spine-like structure (s). Black arrowhead: spine-like structures; magenta arrowhead: vesicles in Fig. S4 B. Scale bars, (A) 1 µm; serial sections, 0.25 µm; (B) 5 µm; (C) 0.5 µm; (E) 5 µm; inset, 0.5 µm.