| Research Abstract |
It has been indicated for long time that Merkel cells, one of the very important cells consisting of cutaneous innervation, were present at the basal portion of the epidermis and regarded as mechano-receptor cells. Recently numerous Merkel cells were observed in the bulge area of the hair follicles of human skin. However, recently Merkel cells were observed in the bulge area of the hair follicles of human skin.
Normal and pathological human skin were investigated in order to clarify the neurogenic keratinizing disorders. Particularly Merkel cells in human skin were studied using anti-cytokearatin 20 monoclonal, antibody and anti-PGP 9.5 polyclonal antibodies by means of immunohistochemistry and electron microscopy, since they are very important cells for investigation of neurogenic cutaneous disorders. It was examined whether or not the Merkel cells were associated with nerve terminals in several regions of the human body using immunohistochemistry techniques. As a result, it was clarif
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ied that Merkel cells showed oval in shape and the expanded nerve terminals were closely associated with them in epidermis. In the bulge, area, however, many dendritic Merkel cells were present. Since the cells protruded the cytoplasmic processes, they showed dendritic in shape. However, the nerve terminals were not attached to the cells. Based on these observation, polymorphism of Merkel cells was identified in human skin.
Approximately 95% of Merkel cells were oval in shaped in epidermis, but many dendritic Merkel cells were present in bulge area of hair follicles. In hair follicles of facial skin, about 30% of them were dendritic and 20% in scalp. On the association of nerve fibers with Merkel cells, discoidal nerve endings were usually attached to the cells in epidermis, but, the Merkel cells in the bulge of hair follicles, nerve fibers were not associated with Merkel cells. Based on our data, it is suggested that the function of dendritic Merkel cells in the bulge area might be different from that of oval-shaped Merkel cells in epidermis. Dermal Merkel cells were often observed by the hair follicles and beneath the epidermis. They showed spherical in shape. It was supposed the possibility that Merkel cells might develop from dendritic cells (immature cells or undifferentiated) and be provided to the epidermis, and that dermal Merkel cells might be on the way to epidermis. It is suggested that dendritic Merkel cells have the function different from sensory receptor. It is suggested that the Merkel cells may release some kind of endocrine substances to accelerate the keratinization of the skin.
Merkel cells and the associated nerve terminals were examined in pathological specimens in the tumors related with hair follicular tissues such as basal cell carcinoma, trichoblastoma, trichoepitherioma, trichilemmal cyst, trichilemmoma, etc. Numerous dendritic Merkel cells were found at the basal edges of the tumor nests in trichoblastoma, but no Merkel cells were seen in basal cell carcinoma. It is considered that Merkel cells may be reliable marker among the tumors undergoing hair follicular keratinization. Further studies are required in the near future. Less
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