Langerhans and Merkel: a nervous epidermal dispute

Excerpt

Paul Wilhelm Heinrich Langerhans junior (Langerhans) (Fig. 1a) was born on the 25th of July 1847 in Berlin into the well-respected family of the family physician Paul August Langerhans and Anna Keibel. At only 17 years of age, he started medical school at the Friedrich-Schiller University of Jena, but changed to Humboldt University of Berlin in order to be taught by Rudolph Virchow. From 1867, Langerhans worked as a student under his mentor Rudolph Virchow. In this institute, he got to know Julius Cohnheim who taught him his famous gold chloride staining techniques. Using this staining method in human skin, Langerhans discovered putative epidermal neurons scattered among the cells of the stratum Malpighi (Fig. 1c). Still being an undergraduate student, he published in 1868 his famous first article “On the nerves of the human skin” (“Ueber die Nerven der menschlichen Haut”) in the present journal [6]. While he was uncertain about their histogenetic nature, their reactivity with gold salts made him believe that “his cells” represented sensory nerve endings. He elaborately described those cells in the epidermis as non-pigmentary cells with button-like dendritic endings and considered them as intraepidermal receptors for extracutaneous signals of the nervous system. His description of the cells was surprisingly precise considering that in 1868, he only had a primitive light microscope for his observations. For more than 100 years, these cells stayed a mystery to dermatologists until Ina Silberberg finally uncovered their immunological importance [13]. In addition, Langerhans was the first to describe granular cells in the upper epidermis [8], the Layer of Langerhans, which remained associated with his name up into the twentieth century, until the dermatological term stratum granulosum became common.

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