Paul Langerhans (25/7/1847 to 20/7/1888) was a German pathologist, physiologist and biologist. He studied the pancreas and noticed unique polygonal cells within the parenchyma of the pancreas. He provided a detailed description of microscopic pancreatic structures. He did not know the significance of these cells at the time of his research. In 1893, the French histologist, G.E. Laguesse, discovered that the polygonal-shaped cells were the endocrine cells of the pancreas that secreted insulin, to be distinguished from the exocrine cells, which secrete digestive enzymes. Laguesse named these endocrine cells the Islets of Langerhans.

ABOUT ISLET OF LANGERHANS

Islet of Langerhans, irregularly shaped patches of endocrine tissue are located within the pancrease. They consist of 4 distinct cell types, of which 3 (alpha, beta, and delta cells) produce important hormones; the 4th component (C cells) has no known function. The common islet cell, beta, produces isulin, the major hormone in the regulation of carbohydrate, fat, and protein metabolism. The release from the beta cells can be triggered by somatotropin or glucagon, but the most important stimulator of insulin release is glucose. The inability of the islet cells to make insulin or the failure to produce amounts sufficient to control blood glucose level is the cause of diabetes mellitus.

Gabriele Falloppio (1523 to 9/10/1562) is often known by his Latin name Fallopius Fallopio and was a famous doctor an surgeon. He is the most illustrious of 16^th century Italian anatomists, who contributed greatly to early knowledge of the ear and of the reproductive organs. Falloppius discovered the tubes that coonect the ovaries to the uterus (now known as fallopian tubes) and several major nerves of the head and face. He described the semicircular canals of the inner ear (responsible for maintaining body equilibrium) and named the vagina, placenta, clitoris, palate, and cochlea.

ABOUT FALLOPIAN TUBE

Fallopian tube, also called oviduct or uterine tube or salpinx is either of a pair of long narrow ducts located in the human female abdominal cavity. It transports the male sperm cells to the egg, provides a suitable environment for fertilization, and transports the egg from the ovary, where it is produced, to the central channel (lumen) of the uterus. Though the name is eponymous, some texts spell it with a lower case ‘f’ from the assumption that the adjective ‘fallopian’ tube has been absorbed into Modern English as the de facto name for the structure.

Sir William Bowman (20/7/1816 to 29/3/1892), 1^st Baronet was an English surgeon, histologist and anatomist. He is mostly famous for his research using microscopes to study various human organs, though during his lifetime he pursued a successful career as an ophthalmologist. He sketched and wrote highly detailed descriptions of the skin, muscle, nerves, sense organs (particularly the eye), kidney, bone, and cartilage. He is probably most  famous, however, for his work on the kidney, in which he indentified the role of a tiny capsule (now known as Bowman’s capsule) in carrying fluid from the kidney to the urinary system.

About Bowman’s capsule

Bowman’s Capsule (Capsula glomeruli or Glomerular capsule) is a double-walled, cup shaped structure around the glomerulus of each nephron of the kidney. It is named after Sir William Bowman. It is also called malphigian capsule. It is a part of the kidney’s filtration system. It serves as a filter to remove organic wastes, excess inorganic salts, and water.

Ranvier was a French histologist and pathologist. He is credited with transforming histology from a descriptive discipline into an experimental science that could serve as a basis for physiological observations. He devoted most of his research to elaborating detailed nerve and skin structure. In 1878 he described constrictions seen in certain nerve fibers, now known as the nodes of Ranvier, where discontinuities occur in the nerve’s myelin sheath, and discovered nerve terminals between the epithelial cells of the tongue that are now known as Ranvier’s tactile disks.

Node of Ranvier

Node of Ranvier is a periodic gap in the insulating sheath (myelin) on the axon of cerain neurons that serves to facilitate the rapid conduction of nerve impulses. Myelin sheath acts as a high-resistance, low-capacitance electrical insulator. However, nodes of Ranvier interrupt the insulation at intervals, and this discontinuity enables impulses to jump from node to node in a process known as saltatory conduction. The action potential propagated by one node of Ranvier jumps to and is regenerated at the next node along the axon, thereby enabling the action potential to travel rapidly along the fibre.