Some New Aspects of Langerhans Cells in the Human Epidermis: Light and Electron Microscopic Observations on the Swelling Sites Seen in the Process Terminals of the Dendritic Cells Described by Langerhans in 1868

In 1868, Langerhans discovered the dendritic cells now generally called Langerhans cells (LCs) in the human epidermis using the gold impregnation method. He pointed out that the terminals of the upward running processes of the cells end with button-like swellings under the cornified layer. In 1951, Ferreira-Marques classified the shapes of the terminals into 7 types, named the largest one Organum trompiforme and reckoned it to be a sense receptor. However, the swellings of the process terminals seem to have been entirely forgotten along with the negation of the nerve cell theory of LCs. The author of this study recovered some of the actual forgotten terminals, the button-shaped (knopff?rmig) swellings of the process terminals of the cells, beneath the cornified layer of a healthy volunteer epidermis using the methylene blue staining method. Furthermore, the ultrastructures of the swellings were captured for the first time using the Thin-Section-Reembedding and Ultrathin-Sectioning (TRUS) technique named by the author. Investigation of the swellings by electron microscopy showed that there were a number of Birbeck granules and vacuoles of various sizes together with elements of cytoskeletons in the cytoplasm. Possibly this shows that LCs play an essential role in the differentiation of the epidermis at the process terminals.