IntroductionNormal human epidermis is mainly composed of keratinocytes ( KC) , Langerhans cells ( LC ) , melanocytes, indeterminate dendritic cells, Merkel cells and lymphocytes.

• 表皮由角质形成细胞(keratinocytes，KC)、朗格汉斯细胞(Langerhans cells，LC)、黑色素细胞、未定型细胞、Merkel细胞、淋巴细胞等组成，其中KC占表皮细胞总数的95%25左右，LC约占表皮细胞总数的2%25-5%25。