Vascular networks of the periphery of the fingernail.

The vascular networks of the periphery of the fingernail have been studied on fingers of adults, foetuses and neonates, by injecting the vascular system with gelatinous Indian ink. The nail is an avascular structure, partially covered by the nail wall. It is lying on the nail bed which is prolonged forwards with the hyponychium. Each part of the nail apparatus presents a characteristic vascular network derived from dorsal collaterals arising from the palmar digital vessels and from their arcades. These networks are papillary, pseudopapillary, reticular and subdermal. Their morphology and density vary according to their localization and correspond with histological variations of the different parts of the nail apparatus. Thus, the germinal part of the nail bed shows poor vascularization. It is responsible for the colour of the lunula. The sterile part and the hyponychium have dense vascular networks with glomus bodies.