Figure 8

Composite diagram showing the schema of interactions and modulation of melanocyte functions. [a] Diagramatic representation of the sympathetic and sensory innervation, the possible pathways for entrainment of the seasonal photophase and light cycles through the melanocyte receptor complexes – melanin units and hair follicles, the cutaneous nerves being utilized as fiberoptic devises. [b] Modulation of the melanocyte cell cycle during the light and dark phases. Serotonin + Melatonin traverse and hold the melanocyte into G2 phase on UV exposure while Melatonin puts it through mitosis. NA, DA, ACTH and tyrosine + dopa enhance pigmentation while acetyl choline is inhibitory.