This is a Langerhans cell. Langerhans cells are dendritic cells found in the epidermis (that is, the uppermost layer of the skin) and should not be confused with the Islets of Langerhans found in the Pancreas – and incidentally named after the same person. Langerhans cells are antigen-presenting cells – in other words, they form part of the body’s protection against antigens, and present these to the immune system.
This is Paul Langerhans. He discovered Langerhans cells at the tender age of 21 (that’s younger than I am now). He did mistakenly believe they were part of the nervous system due to their dendritic appearance – but whatever. It was not long thereafter that he wrote a paper on the anatomy of the pancreas and referred especially to the Islets of Langerhans, which we all know and love.
Upon further reading up, I found rather disappointingly that Langerhans did not really have any ideas what either of these structures did, just that they existed. That’s less remarkable… and somehow I doubt that these days anyone will be so acclaimed for similar discoveries.
But again… he did make a fairly cool discovery at a young age. I suppose maybe those days you weren’t considered a dimwit or a baby at 21. Also, life expectancy was considerably lower those years, and Langerhans went on to develop Tuberculosis and eventually die at age 41.