Sprouty/FGF Signaling Regulates Proximal–Distal Feather Morphology and Dermal Papillae Size

The study investigated the role of Sprouty (Spry) and Fibroblast Growth Factor (FGF) signaling in feather development, focusing on how these pathways influenced feather morphology and dermal papillae size. It was found that overexpression of Spry4 promoted feather branching at the expense of proximal structures, leading to feathers with expanded vane regions and reduced calamus. In contrast, overexpressing Fgf10 increased dermal papillae size and expanded proximal structures but inhibited feather branch formation. These findings suggested that the balance of Sprouty/FGF activity was crucial for modulating feather stem cells, influencing the size and shape of feather components, and highlighted the importance of Sprouty modulation of FGF activity for normal feather development.