Topography and vascularization of brown fat in a hibernator (little brown bat, Myotis lucifugus)

Abstract

Thirteen identifiable deposits of brown fat occur in the little brown bat, Myotis lucifugus. Drawings of these deposits and their vascular supply are presented. Blood vessels were distinguished during dissection by filling the circulatory system with methyl methacrylate. The findings demonstrate the potential of brown fat to transfer heat efficiently to the blood during arousal from hibernation, thereby providing further evidence in support of a thermogenic role for this tissue.

Myotis lucifugus

“…The amount of brown fat in M. lucifugus also shows seasonal variation. There are 13 topographically distinct deposits of brown fat in this species, situated to transfer heat to the blood efficiently and rapidly during arousal from hibernation (Rauch andHayward, 1969, 1970). When the ambient temperatures fall below their thermal neutral zone (32 to 36?C winter; 39 to 42?C summer; Stones and Wiebers, 1967), little brown bats readily enter torpor as a means of conserving energy rather than as a reflection of poor thermoregulatory ability.…”