Meeting Abstract
Bats are the only mammals capable of powered flight. Aerial locomotion is achieved with wings composed of bilayered skin. Among other elements, the skin contains muscles and organized bundles of elastin fibrils. One set of muscles, the plagiopatagiales proprii (mpp), are variable in form but present in all bats studied so far; the mpp may control camber of the wing during downstroke. The mpp are unusual in that they do not have skeletal attachments. We investigated the caudal and rostral insertion points of the mpp in two species of phyllostomid bats, Carollia perspicillata and Artibeus lituratus. Wing tissue was fixed and processed for histology. The caudal insertion was similar in both species: each mpp attached via collagen to a spanwise elastin fiber near the trailing edge of the wing. The rostral end revealed differences between species. In C. perspicillata, most muscle cells in an mpp bundle terminated on a spanwise elastin fiber. A few muscle cells extended rostrally and their collagen wrapping (endomysium) appeared continuous with the surrounding collagenous matrix. In A. lituratus, each mpp terminated in a tendon continuous with collagen that organizes the muscle bundle (endomysium and epimysium). This tendon is uniquely embedded with numerous elastin fibrils. Rostrally, the elastin-collagen tendon intersected spanwise elastin fibers in the armwing. In both species, the attachments might allow the mpp to distribute contractile force across the wing via the mesh-like elastin network. Bat wings are thin, resilient, flexible and aeromechanically complex. Understanding the microstructure, arrangement, and interactions among the wing elements will improve our understanding of bat flight and might inspire the design of lightweight, compliant, and active materials that can withstand aerodynamic loads.
