Paul Langerhans was a German biologist, physician, and physiologist who was the first scientist to describe the pancreatic islets that secrete insulin, now known as islets of Langerhans. He also served as a professor at the University of Freiburg.
Background
Paul Langerhans was born Paul Wilhelm Heinrich Langerhans on July 25, 1847, in Berlin, Germany. His father, Paul August Hermann Langerhans, was a well-known physician in Berlin; his mother was Anna Luise Caroline Keibel. His two younger stepbrothers were also physicians. One of them, Robert, was an assistant to Virchow and later became a professor of pathology.
Education
Langerhans attended the Gymnasium zum Grauen Kloster in Berlin and graduated at the age of sixteen. From 1865 to 1866 he studied medicine at the University of Jena, where he was much impressed by Haeckel and Gegenbaur. He continued his medical studies in Berlin under K. Bardeleben, E. du Bois-Reymond, R. Virchow, J. Cohnheim, and F. T. von Frerichs. In 1869 he graduated with the Doctor of Medicine degree.
At Berlin, Langerhans was particularly influenced by Virchow and Cohnheim, and he became later a close friend of Virchow’s. His first important research was done in Virchow’s laboratory, where he discovered the cell islands of the pancreas named after him.
In 1870 Langerhans accompanied the geographer Heinrich Kiepert on an expedition to Egypt and Palestine. During the Franco-Prussian War, he joined the German army as a physician and worked in a military hospital. After the conclusion of peace, he went for a short while to Leipzig to see Ludwig’s famous physiological institute and the obstetrical clinics of K. S. F. Crédé. In 1871 he was offered the position of prosector in pathology at the University of Freiburg im Breisgau, where he also became privatdozent in the same year and, later, associate professor. In 1874 tuberculosis of the lung compelled Langerhans to interrupt his academic career. Attempts at cure in Switzerland, Italy, and Germany failed; and in 1875 he settled in Madeira. Its mild climate led to an improvement in his health. In Madeira he later practiced medicine in the capital, Funchal, where he died of a kidney infection.
Langerhans’ main scientific achievements consist of his studies of human and animal microscopical anatomy. In this field, he was among the first successful investigators to explore the new area of research with novel methods and staining techniques. Langerhans made his first scientific contributions as a medical student in Virchow’s laboratory, under the guidance of Virchow and especially of Cohnheim. In 1868 he published a paper on the innervation of the skin; he had used gold chloride as a stain. He was able to show nerve endings in the Malpighian layer of the epidermis and described characteristic oblong bodies with branching processes in the Malpighian layer (later called Langerhans’ cells). He believed that these bodies were probably nerve cells, but he did not exclude the possibility that they might be pigment cells (later called dendritic cells).
In his inaugural dissertation (1869) Langerhans immortalized his name by his discovery of characteristic cell islands in the pancreas named for him. The investigations for this work, Beiträge zur mikroskopischen Anatomie der Bauchspeicheldrüse, were conducted in Virchow’s pathology laboratory. The paper presented the first careful and detailed description of the microscopic structure of the pancreas.
Langerhans examined mainly the pancreas of rabbits. He studied fresh tissue and even sought to make microscopic observations of pancreatic tissue in the living animal. His main results were obtained through chemical fixation and maceration. Langerhans injected the pancreatic duct with Berlin blue in order to show the branching and the structure of the excretory system. Examining portions of the fresh gland, he distinguished three zones in the secreting cells: an apical granular zone, the zone of the cell nucleus, and a clear basal zone. In macerated pancreatic tissue he differentiated various types of cells, including small, irregularly polygonal cells without granules. These cells formed numerous spots scattered through the parenchyma of the gland measuring 0.1-0.24 mm. in diameter. Langerhans refrained from making any hypothesis as to the nature and significance of these cells. In 1893 the French histologist G. E. Laguesse named these cell spots “islets of Langerhans”; the insulin-secreting function of these cells was established later.
Another important contribution, made with F. A. Hoffmann in Virchow’s laboratory, dealt with the macrophage system. Langerhans and Hoffmann studied the intravital storage of cinnabar injected intravenously in rabbits and guinea pigs. After the injection, they sought the presence of cinnabar in the blood and all the organs except the spleen. They were able to show that cinnabar was taken up by white blood corpuscles but never by the red. They also demonstrated the deposit of cinnabar in fixed cells of the bone marrow, in the capillary system, and in the connective tissue of the liver. This was one of the pioneer investigations that later led to Aschoff's concept of the reticuloendothelial system.
In 1873 Langerhans studied the structure of the skin and its innervation, staining the preparations with osmic acid and picrocarmine. He observed the nerve fibers branching in the interior of Meissner’s corpuscles and described the oblong cells lying transversely in these corpuscles. In the report on this study, Langerhans described his discovery of the granular cells in the exterior portion of the Malpighian layer (Langerhans’ layer, stratum granulosum). In 1873 and 1874 Langerhans examined the microscopic structure of the cardiac muscle fibers in vertebrates and of the accessory genital glands of man. One of his last extensive histological papers (1876) was dedicated to the anatomy of the amphioxus.
During his trip to Palestine, Langerhans, stimulated by Virchow’s interest in anthropology, made skull measurements and anthropological observations of the population of Palestine. In the last decade of his life, while practicing medicine on Madeira, Langerhans studied the etiology of tuberculosis. During that time he also published a handbook on Madeira dealing with the climatic and curative properties of that island.
Paul Langerhans's main scientific achievements consist in his studies of human and animal microscopical anatomy. In this field he was among the first successful investigators to explore the new area of research with novel methods and staining techniques. He is credited with the discovery of the cells that secrete insulin, named after him as the islets of Langerhans. Langerhans also dealt with the macrophage system, where he was able to show that cinnabar was taken up by white blood corpuscles. His another contribution was his study of the structure of the skin and its innervation, where he described his discovery of the granular cells in the exterior portion of the Malpighian layer, now named Langerhans's layer.
In 1885, Langerhans married Louise Emilie Margarethe Ebert, née Jordan, the widow of one of his patients. They traveled to Berlin for the wedding, and he met his father, sisters and two brothers for the last time. The newly-weds rented Quinta Lambert, known as the most beautiful villa in Funchal and now the Official Residence of the President of the Regional Government. In the words of his new bride “three indescribably happy years” followed.