A particular form of adipose tissue with selected distribution. It differs from white adipose tissue both structurally and functionally; its colour is brownish (yellow to reddish), depending on its content of (mitochondrial) cytochromes and of fat which is distributed in multipledroplets (multilocular) as compared to white fat cells (monolocular) and also on its dense vascularization. Brown adipose tissue appears to be restricted to mammalian species, especially of smaller body size, including the hibernators (-Hibernation), but is also present in newborns of larger species including humans. Regulatory heat production has been identified as its main but possibly not its only function.
