Volar adhesive pads of the feathertail glider, Acrobates pygmaeus (Marsupialia; Acrobatidae)

Abstract

The feathertail glider (Acrobates pygmaeus) is a mouse-sized marsupial that can cling to and run on smooth vertical panes of glass. To understand this remarkable ability, a comparative histological study of pads on the volar surface of the pes and manus of four species of marsupials was completed. Acrobates pygmaeus and Cercartetus concinnus have well-developed volar pads that consist of epidermal ridge - sweat gland complexes. Such pads are less developed in Tarsipes rostratus and are not externally visible in Sminthopsis crassicaudata. In addition to its possible role in capillary adhesion, the epidermal ridge - sweat gland complex of A. pygmaeus has a unique epidermal histo-architecture. Here, the stratum corneum consists of horizontal rows of cell remnants that do not become flattened or adpressed to form a stratified squamous epithelium. It is proposed that the tall stratum corneum resists shear and compression that develop when the feathertail glider completes a glide.