Specialised Vascular Structures in the Pododerma of the Camel Footpad (Camelus dromedarius)

Abstract

Aims: The even‐hoofed, unguligrade tylopods display a well‐developed eponymous footpad that absorbs most of the body weight in locomotion and is particularly adapted to the sandy ground surface of the natural environment of dromedaries. Considering the drastic changes in temperature occurring in the desert sand, specialised thermoregulatory vascular and nervous structures are to be expected in the modified pododerma of this footpad. Therefore, the aim of the study was to demonstrate the angioarchitecture of the camelid footpad and to detect specialised vascular structures related to these specific functions.Material and Methods: Corrosion casting of fore and hind feet of dromedaries (Camelus dromedarius); scanning electron microscopy of micro‐corrosion castsResults and Discussion: The dense angioarchitecture of the dromedary footpad, like that of unmodified skin, can be subdivided into separate plexus arranged at different levels: a subcutaneous plexus, a profound dermal plexus, a superficial dermal plexus and a subepidermal plexus.The subepidermal blood vessels run very close to the dermo‐epidermal borderline and thus the subepidermal angioarchitecture consists of densely vascularised conical papillae comprised of centrally situated papillary arteriole and venule ensheathed in a dense subepidermal capillary network. At the tip of the papillae, the central papillary arteriole and venule form a peripheral capillary loop, acting as a thoroughfare channel. This dermal angioarchitecture of the dromedary footpad is comparable to the papillary system described in the bulbs of the highly specialised digital end organs of many other odd‐ and even‐hoofed mammals, particularly the equine hoof and the bovine claw.Within the subcutaneous and the deep dermal plexus of the dromedary foot pad, unique glomus‐like vascular structures were detectable, presumably associated with cutaneous thermoregulation as described for the unmodified hairy skin.