Functional morphology of the trunk and paw pad skin of the African palm squirrel (Epixerus ebii)

The study was initiated to contribute to the meager knowledge of the anatomy of the African palm squirrel. Skin of the trunk and paw pads was the subject of interest. Basic gross and histological techniques were employed. The dorsal fur was grey with golden brown free endings, while the ventral fur was greyish white. The fur covered the entire trunk, extended through the dorsal surface of the distal carpal joint to the dorsal surface of the digits. Five digital pads, three inter-digital pads and two metacarpal pads were observed on the forefoot. There was no observable digital pad on the hind foot; four inter-digital and two metacarpal pads were observed. Surface grooves were evident in the cornified layer of the trunk skin, but not in the paw pad skin. The mean thickness of the cornified layer of the epidermis of the palmar pad was 75.54±3.45 μm, while the entire epidermis was 102.32±4.23 μm thick. The non-cornified layer of the trunk skin was made of only three distinct layers, as the stratum lucidum was not evident. Conversely, the stratum lucidum was evident in the paw pad skin. Dermal papillae observed in the paw pad skin were more numerous and progressed deeper into the non-cornified epidermis than those observed in the trunk skin. There were more melanocytes in the dorsal than in the ventral trunk skin. The study concluded that the trunk and paw pad skin of the African palm squirrel enable its adaptation to arboreal habitat.