Bragulla Hermann, Hirschberg Ruth M
Department of Veterinary Anatomy, Freie Universität Berlin, D-14195 Berlin, Germany.
J Exp Zool B Mol Dev Evol. 2003 Aug 15;298(1):140-51. doi: 10.1002/jez.b.31.
Accessory organs of the integument are locally modified parts of the potentially feather-bearing skin in birds (e.g., the rhamphotheca, claws, or scales), and of the potentially hairy skin in mammals (e.g., the rhinarium, nails, claws, or hooves). These special parts of the integument are characterised by a modified structure of their epidermal, dermal and subcutaneous layers. The developmental processes of these various integumentary structures in birds and mammals show both similarities and differences. For example, the development of the specialised epidermal structures of both feathers and the hoof capsule is influenced by the local three-dimensional configuration of the dermis. However, in feathers, in contrast to hooves, the arrangement of the corneous cells is only partially a direct result of the particular arrangement and shape of the dermal surface of the papillary body. Whereas the diameter of the feather papilla, as well as the number, length, and width of dermal ridges on the surface of the feather papilla influence the three-dimensional architecture of the feather rami, there is no apparent direct correlation between the dermo-epidermal interface and the development of the highly ordered architecture of the radii and hamuli in the feather vane. In order to elucidate this morphogenic problem and the problem of locally different processes of keratinisation and cornification, the structure and development of feathers in birds are compared to those of the hoof capsule in horses. The equine hoof is the most complex mammalian integumentary structure, which is determined directly by the dermal surface of the papillary body. Perspectives for further research on the development of modified integumentary structures, such as the role of the dermal microangioarchitecture and the selective adhesion and various differentiation pathways of epidermal cells, are discussed.
皮肤的附属器官是鸟类潜在着生羽毛皮肤的局部特化部分（如角质喙、爪子或鳞片），以及哺乳动物潜在着生毛发皮肤的局部特化部分（如鼻镜、指甲、爪子或蹄）。这些皮肤的特殊部分其表皮、真皮和皮下层结构均有改变。鸟类和哺乳动物这些不同皮肤结构的发育过程既有相似之处，也有不同之处。例如，羽毛和蹄匣的特化表皮结构的发育受真皮局部三维结构的影响。然而，与蹄不同，羽毛中角质细胞的排列只是部分直接取决于乳头体真皮表面的特定排列和形状。虽然羽毛乳头的直径以及羽毛乳头表面真皮嵴的数量、长度和宽度会影响羽枝的三维结构，但真皮 - 表皮界面与羽片中高度有序的羽干和小钩结构的发育之间没有明显的直接关联。为了阐明这个形态发生问题以及局部不同的角质化和角化过程问题，将鸟类羽毛的结构和发育与马的蹄匣进行了比较。马蹄是最复杂的哺乳动物皮肤结构，它直接由乳头体的真皮表面决定。文中还讨论了对特化皮肤结构发育进行进一步研究的前景，如真皮微血管结构的作用以及表皮细胞的选择性黏附与各种分化途径。
