Topology of Feather Melanocyte Progenitor Niche Allows Complex Pigment Patterns to Emerge

The study explored the cellular and molecular mechanisms behind feather pigment pattern formation in birds. It found that melanocyte progenitors are arranged in a horizontal ring in the proximal follicle, sending melanocytes upward as feathers grow. Pigment patterns are influenced by the modulation of melanocyte presence, arrangement, or differentiation, and are further regulated by agouti expression in the peripheral pulp. The cyclic regeneration of feathers resets pigment patterns to meet physiological needs, suggesting that the evolution of stem cell niche topology enabled complex pigment patterns through simple regulatory mechanisms.