A new type of somatosensory organ in the nasolabial skin of the dog

Abstract

A new morphological type of somatosensory organ is described. It is found in the glabrous skin of the dog nose (rhinarium or planum nasale) and situated in dermis papillae. The otherwise thick epidermis forms a thin window above the organ. There are only a few layers of keratinocytes in the window and the corneocytes are much thinner than elsewhere. The organ consists of highly branching cells that wrap naked nerve endings emanating from myelinated nerve fibers originating in the outer dermal nerve plexus. The structure entirely fills the top of the dermal papilla. The intercellular spaces of the organ and its surroundings are occupied by an extended areolar basal lamina.

Rhinarium skin structure and epidermal innervation in selected mammals

“…The most distinct and unique feature in dog rhinarium epidermal domes is the heavily innervated dermal sensory organ in the top of the central dermal papillae. A recent electron microscopy study has classified it as a new morphological type of somatosensory skin organ (Elofsson & Kröger, 2020).…”

“…Dog rhinarium skin has been described as densely innervated by free epidermal nerve fibers, but with low densities of more complex skin sensory organs (Abe, 1954). A recent electron microscopy study described a new morphological type of somatosensory skin organ in dog rhinarium skin (Elofsson & Kröger, 2020). As the organ is nonencapsulated, it was suggested to detect cues other than mechanical stimuli.…”