title: The structural design of the bat wing web and its possible role in gas exchange.
abstract: The structure of the skin in the epauletted fruit bat (Epomophorus wahlbergi) wing and body trunk was studied with a view to understanding possible adaptations for gas metabolism and thermoregulation. In addition, gas exchange measurements were performed using a respirometer designed for the purpose. The body skin had an epidermis, a dermis with hair follicles and sweat glands and a fat-laden hypodermis. In contrast, the wing web skin was made up of a thin bilayered epidermis separated by a connective tissue core with collagen and elastic fibres and was devoid of hair follicles and sweat glands. The wings spanned 18-24 cm each, with about 753 cm2 of surface exposed to air. The body skin epidermis was thick (61 +/- 3 microm, SEM), the stratum corneum alone taking a third of it (21 +/- 3 microm). In contrast, the wing web skin epidermis was thinner at 9.8 +/- 0.7 microm, with a stratum corneum measuring 4.1 +/- 0.3 microm (41%). The wing capillaries in the wing web skin ran in the middle of the connective tissue core, with a resultant surface-capillary diffusion distance of 26.8 +/- 3.2 microm. The rate of oxygen consumption (VO2) of the wings alone and of the whole animal measured under light anaesthesia at ambient temperatures of 24 masculineC and 33 masculineC, averaged 6% and 10% of the total, respectively. Rate of carbon dioxide production had similar values. The membrane diffusing capacity for the wing web was estimated to be 0.019 ml O2 min(-1) mmHg(-1). We conclude that in Epomophorus wahlbergi, the wing web has structural modifications that permit a substantial contribution to the total gas exchange.
authors.affiliation: Department of Veterinary Anatomy & Physiology, University of Nairobi, Kenya. makanya@uonbi.ac.ke
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Makanya
authors.forename: Jacopo P
authors.initials: JP
authors.lastname: Mortola
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002196:Capillaries / Q000033:anatomy & histology; D002245:Carbon Dioxide / Q000378:metabolism; D002685:Chiroptera / Q000033:anatomy & histology / Q000502:physiology*; D004058:Diffusion; D005740:Gases; D008854:Microscopy, Electron; D010100:Oxygen / Q000378:metabolism; D015657:Respiratory Transport; D012879:Skin Physiological Phenomena; D012881:Skin Temperature; D014921:Wings, Animal / Q000033:anatomy & histology* / Q000502:physiology*
chemical_list: D005740:Gases; D002245:Carbon Dioxide; D010100:Oxygen