Regional differences in the skin of the desert hedgehog (Paraechinus aethiopicus) with special reference to hair polymorphism

The present investigation aims to describe the morphometric and histological features of the skin in the desert hedgehog (Paraechinus aethiopicus). Skin biopsies were harvested from the dorsal, abdominal, labial, and nasal regions to monitor the structural differences. Histologically, the skin followed the general mammalian architectural pattern and was composed of three main layers; epidermis, dermis, and hypodermis. However, there were some species-specific differences. The hairless skin of the rhinarium was the thickest and no sebaceous gland was detected. Moreover, the lateral nasal glands were recorded for the first time in hedgehogs. This feature is very common in mammals that utilize thermal panting strategy rather than sweating in thermoregulation. The histological analysis of the dorsal and ventral skin confirmed our observation, as no sweat gland was detected. The labial glands were overpopulated in the skinny surface of the upper lip, while the vermillion border devoid glands at all. Hedgehog’s hair exhibited morphological and structural modifications. The dorsal skin exhibited stiff spines, while the belly skin was covered by dense fur. The vibrissal hairs were located on the snout and regularly arranged on both sides of the labial skin, embedded in the blood sinus system and enveloped within a dense collagenous capsule. Together, these data suggest that the desert hedgehog has a unique integumentary system enabling him to accommodate the extreme environmental conditions of the desert habitat.