Elofsson Rolf, Kröger Ronald H H
Unit of Functional Zoology, Department of Biology, Lund University, Lund, Sweden.
J Morphol. 2018 Aug;279(8):1194-1198. doi: 10.1002/jmor.20842. Epub 2018 Jun 6.
The usual pigmentation pattern in mammalian skin consists of fixed melanocytes in the basal layer of the epidermis, supplying keratinocytes with melanosomes. We observed that the glabrous skin (rhinaria and footpads) of dogs deviates from this pattern. In dogs, melanocytes are found in both the dermis and epidermis. The epidermal melanocytes are situated in the intercellular spaces of the basal and spinous layers. They are characterized by a quantity of cytoplasm containing a centriole, also developing melanosomes, and in some cases annulate lamellae. There is a high frequency of closely apposed melanocytes in the epidermis. Melanosomes in different stages of formation are also abundant. The morphology of the glabrous skin of dogs suggests transport of melanocytes from the dermis into the epidermis and formation of melanosomes in the epidermis. A distributed and intense pigment formation may be necessary to achieve the black noses of many dog breeds and wild canids, as well as dark footpads despite heavy abrasion and rapid skin renewal.
哺乳动物皮肤中常见的色素沉着模式是由表皮基底层中的固定黑素细胞组成，这些黑素细胞为角质形成细胞提供黑素小体。我们观察到狗的无毛皮肤（鼻镜和脚垫）偏离了这种模式。在狗身上，真皮和表皮中都发现有黑素细胞。表皮黑素细胞位于基底层和棘层的细胞间隙中。它们的特征是含有一定量的细胞质，其中有一个中心粒，也在形成黑素小体，在某些情况下还有环状片层。表皮中紧密相邻的黑素细胞频率很高。处于不同形成阶段的黑素小体也很丰富。狗无毛皮肤的形态表明黑素细胞从真皮转运到表皮，并在表皮中形成黑素小体。尽管有严重磨损和皮肤快速更新，但许多犬种和野生犬科动物的黑色鼻子以及深色脚垫可能需要分布广泛且强烈的色素形成。
