Aspects of the Form and Function of the Kidney of the Honey Possum, Tarsipes-Rostratus

Abstract

The morphology and concentrating-diluting capacity of the kidneys of the honey possum, Tarsipes rostratus, is appropriate for its nectarivorous diet. The cortex is wide with many glomeruli, the medulla is thin and undivided. Calculated maximal urinary concentration (1469 mOsm kg-' H2O) agrees closely with actual urinary concentrations measured under conditions of low water availability (1350 mOsm kg-' H2O). The honey possum appears to be naturally polydipsic and polyuric, and capable of ingesting 2000 ml kg-' bodyweight day-' and urinating 800 ml kg-' bodyweight day-' in order to maintain fluid homeostasis. Comparative renal morphology of seven other species of small mammals with different diets was also determined. Except for Cercartetus concinnus, which may be partially nectarivorous, the renal medulla of other small marsupials and eutherians is thick and subdivided.