![]() Our broader histological survey of white rhinoceros skin identified glands similar in morphology to those reported in skin from the flank of the black rhinoceros, Diceros bicornis. However, the integument of other body regions of the white rhinoceros were not studied histologically and visual observation of the external surface of the skin found no hairs protruding on the surface. These glands were associated with small hair follicles that do not reach the surface and poorly developed sebaceous glands that lubricate the skin. Cave and Allbrook, described glands in white rhinoceros integument in the nuchal region, which they classified as apocrine sweat glands due to their large lumen. We identified large, simple, coiled tubular sweat glands in the dermis near its junction with the epidermis. ![]() These glands are hypothesized to play a role in evaporative heat loss to compliment conductive heat loss in the water. Integument of the common hippopotamus ( Hippopotamus amphibious) also contains hair follicles and lacks sweat glands in the dermis however, there are sparse compound tubuloacinar subdermal glands (between the dermis and superficial fascia) that secrete mucous and serous products onto the skin surface of the flank and dorsum. Elephant body cooling occurs through evaporative heat loss via non-sweating transepidermal water loss and convective heat transfer, largely via vascular networks in the ears. For example, African elephant ( Loxodonta africana) dermis contains hair but lacks sweat glands. White rhinoceros hair and gland integumentary histology are in contrast with other large land mammals that inhabit Africa. In this study, we investigate integumentary histology of the white rhinoceros from skin sampled from multiple body regions. Lastly, integumentary neurovascular supply has not been fully described. Also, while rhino dermal collagen microstructure has been investigated, other aspects of white rhinoceros dermis have not been characterized. Currently, little data exists regarding the abundance of sweat glands and hair in white rhinoceros skin except for one study of integument from the nuchal region. Also part of the integumentary system are epidermal appendages, including glands, hair and nails. Both of these layer have components that contribute to the toughness of the skin, such as desmosomes of the epidermis and collagen bundles of the dermis. It is comprised of a superficial epithelial layer called the epidermis and a deeper layer of connective tissue called the dermis, which contains neurovasculature that supplies the skin. The skin is an important organ system that not only serves as a barrier between an organism and its environment, but helps maintain homeostasis necessary for survival. Fish and Wildlife Service and the World Wildlife Fund. However, many histological characteristics of the rhinoceros integumentary system remain unknown or poorly described because of a scarcity of available samples for study there are fewer than 25,000 white rhinoceros, which are designated as threatened by the U. This species is known for its thick skin, often referred to as dermal armor, which has a dense, cornified epidermis and a dermis with high tensile strength. The third largest herbivore and the largest species of Rhinocerotidae is the white rhinoceros, or squared-lipped rhinoceros, Ceratotherium simum. ![]() ![]() Together, these data suggest the white rhinoceros has a unique integumentary system among large terrestrial herbivores. Simple coiled sweat glands were present in the dermis, but hair and sebaceous glands were absent. Collagen fiber bundles were thickest in the flank (210.9 μm) followed by shoulder, rump and cheek. Most of the dermal thickness consisted of organized collagen bundles with scattered elastic fibers. The epidermal-dermal junction was characterized by abundant papillary folds increasing surface contact between integument layers. Numerous melanin granules were found in the basal and spinosum layers. The stratum corneum comprised more than half the epidermal thickness. The epidermis was thickest in the flank (1.003 mm) followed by the rump, cheek and shoulder. Skin samples from the cheek, shoulder, flank and rump were taken from a 46-year-old female southern white rhinoceros and examined using H&E and elastic histological stains. In this study, we report findings from a microscopic analysis of the white rhinoceros ( Ceratotherium simum) integumentary ultrastructure.
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