Rhinarium skin structure and epidermal innervation in selected mammals.

Area of Science:

• Comparative anatomy
• Neuroscience
• Mammalian biology

Background:

• The rhinarium (planum nasale) is the glabrous skin around mammalian nostrils.
• It possesses epidermal domes and is innervated by the trigeminal nerve.
• Its sensory role is linked to touch, chemical, and temperature stimuli.

Purpose of the Study:

• To correlate rhinarium skin sensory innervation variations with feeding behaviors across diverse mammalian species.
• To investigate skin morphology, nerve fiber density, and distribution within rhinarium epidermal domes.

Main Methods:

• Histological and immunohistological analyses were employed.
• Studied four species: cow, ring-tailed lemur, brown bear, and dog, representing varied feeding behaviors.
• Examined skin morphology, nerve fiber density, and distribution in epidermal domes.

Main Results:

• All species showed similar rhinarium skin morphology; glands were unique to cows.
• Significant innervation pattern differences were observed.
• Mechanosensory organs were found only in ring-tailed lemurs; dogs had a central dermal papilla with a nerve bundle.
• Abundant free epidermal nerve fibers suggest sensory roles in all species.

Conclusions:

• Rhinarium skin functions as a sensory surface for detecting fine touch, chemicals, and temperature.
• Epidermal domes can be considered functional units, with nerve distribution and central structures (glands in cows, dermal papilla in dogs) playing key roles.
• Observed innervation differences indicate diverse sensory functions of mammalian rhinaria, potentially linked to feeding behaviors.