Paul Langerhans is known primarily for his microscopic anatomical research. Langerhans, who was from a family of physicians, was born in Berlin on July 25, 1847. He attended the Gymnasium zum Grauen Kloster, and studied medicine at the University of Jena, and later in Berlin, where he received his medical degree in 1869. As a student, Langerhans developed new cell staining techniques and, using gold chloride as a stain, was able to identify nerve endings in the Malpighian layer of the skin, which were later called Langerhans cells. Applying another one of his staining techniques, Langerhans studied the pancreas (mainly rabbits), and, during his research, noticed unique polygonal cells within the parenchyma of the pancreas. He subsequently used his pancreas research as the topic for his dissertation and was the first to provide a detailed description of microscopic pancreatic structures. Langerhans did not know the significance of these cells at the...