Human skin as revealed by optical and electron microscopy / 全日本鍼灸学会雑誌

ABSTRACT

[Objective]The skin is the biggest organ in the body. The human epidermis functions as a defence against various antigens in addition to physical and bio-chemical protection. The dermis consists of dense connective tissue which contains the circulatory system and sensory nerve endings. In this paper, regional differences in the structures of human skin are described.<BR>[Materials and Methods]The skin of different regions in the human body was examined by optical and electron microscopy and by utilizing various morphological techniques. <BR>[Results and Discussion]EpidermisThe cornified layer in the finger pulp and heel, which receives strong mechanical stimuli, is considerably thicker than other regions. The germinal layer consisting of spinous and basal layers becomes thinner with aging. Langerhans cells that produce antigens are scattered in the germinal layer. Furthermore, Merkel cells situated at the basal layer are found in the finger pulp, bottom of the foot and the hair disks of limbs. These cells are involved in the sense of touch or pressure. DermisThe dermis is divided into the papillary and reticular layers, which consist of loose and dense connective tissue, respectively. In the papillary layer, fibrocytes and mast cells are distributed. Large-sized dermal papillae are found the in finger pulp and bottom of the foot, but there are also a few small papillae in other regions. In large papillae, loops of blood capillaries and Meissner's tactile corpuscles were observed. In addition, large-sized lymphatic capillaries are present in the papillary layer.A dense network of free endings, which are situated beneath the epidermis and are responsible for thermal nociception, are abundant in the face, palm, forearm and sacrum. Corpuscles of Vater-Pacini situated in the deep dermis or subcutaneous tissue are found in the finger pulp, and bottom of the foot. <BR>[Conclusion]In conclusion, it is likely that acupuncture and moxibustion may directly or indirectly stimulate Langerhans cells, Merkel cells, fibrocytes, mast cells or various nerve endings.