Melanophores inside Frogs

Melanocytes/melanophores were known for some decades as pigment cells in skin. The origin of these cells in embryogenesis from neural crest cells is actively investigated now. Some melanocytes/melanophores were described inside adult vertebrates. Historically, these internal melanocytes have been largely ignored, until recently. In frogs, the melanophores populate not only the skin, but all the inner connective tissues: epineurium, peritoneum, mesentery, outer vascular layer and skin underside. In adult avian, melanocytes were also found in visceral connective tissues, periostea, muscles, ovaries and the peritoneum. In mammals and humans, melanocytes are also revealed in eyes, ears, heart and brain. A black-brownish pigment, which can be found in brains of humans and some mammals, was called neuromelanin. Currently, attempts are being made to treat neurodegenerative diseases and various nerve injuries with medications containing melanin. In this micro-review, we wanted to remind again about the inner melanophores on visceral organs and lining blood vessels and nerves, their importance in organisms resistance to adverse environmental factors.