Franz von Leydig

Born 1821
Died 1908

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German zoologist and comparative anatomist, born May 21, 1821, Rothenburg ob der Tauber; died April 13, 1908, Rothenburg ob der Tauber.

Biography of Franz von Leydig

Franz von Leydig's work on neural tissue influenced the great Norwegian zoologist and polar explorer Fridtjof Nansen (1861-1931) who shared with Wilhelm His (1841-1904) and Auguste-Henri Forel (1848-1931) priority in establishing the anatomical entity of the nerve cell.

One of three children, Leydig was the only son of Melchior Leydig, a Catholic and a minor public official, and his wife Margareta, a Protestant. Leydig shared his father’s religion as well as his hobbies, the older Leydig being a keen gardener and beekeeper. Leydig himself later recalled that these childhood interests established his lifelong concern with botany and zoology. At the age of twelve the boy acquired a simple microscope, at which he spent most of his free time.

Leydig studied philosophy in Munich from 1840, medicine in Würzburg from 1842 under Martin Münz (1785-1848), Schenk, and Franz von Rinecker (1811-1883). He received his doctorate in medicine at Würzburg on August 27, 1847, and became an assistant in the department of physiology, teaching also histology and developmental anatomy under Rudolf Albert von Kölliker (1817-1905). He became prosector at the zootomic institution in Würzburg in 1848, qualified as a university lecturer in 1849, and became professor extraordinary on May 9, 1855. In the winter of 1850-1851, Leydig made a trip to Sardinia, where he became aware of the rich marine life that was to become the subject of some of his most important researches. This journey, coupled with his early preoccupation with microscopy, determined the course of his life’s work.

In 1857 Leydig was appointed full professor of zoology and comparative anatomy at the University of Tübingen and published his Lehrbuch der Histologie des Menschen und der Tiere, his outstanding contribution to morphology. In his introduction to the Lehrbuch, Leydig reviewed the crucial developments in the history of histology, including the discovery and definition of the cell by Jan Evangelista Purkyne 1797-1869), Gabriel Gustav Valentin (1810-1883), and Theodor Ambrose Hubert Schwann (1810-1882), the last of whom described it as a vesicle containing a nucleus in 1839. Leydig paid further tribute to other contemporary anatomists, particularly Johannes Peter Müller (1801-1858) for his work on glands and for the emphasis that he properly placed upon the significance of the cellular doctrine for pathology. Leydig’s book was published at about the same time as other general treatments of similar subjects - most notably Kölliker’s Handbuch der Gewebelehre des Menschen (1852) and Joseph von Gerlach’s (1820-1896) Handbuch der allgemeinen und speciellen Gewebelehre des menschlichen Körpers . . . (1848). The Lehrbuch, however, gives the best account of the rapid growth of comparative microscopical anatomy in the two decades following Schwann’s discoveries.

In addition to its historical importance, Leydig’s Lehrbuch is significant for his description in it of a large secretory cell, found in the epidermis of fishes and larvae amphibians. This mucous cell is peculiar in that it does not pour it secretion over the surface of the epithelium; Leydig believed that its function was to lubricate the skin and the cell now bears his name.

Chief among Leydig’s other discoveries is the interstitial cell, a body enclosed within a smooth endoplastic reticulum and containing lipid granules and crystals, that occur in the seminiferous tubules and in the mediaseptum and connective-tissue septa of the testes. These cells are believed to produce the male hormone testosterone, which determines male secondary sexual characteristics. Leydig described the interstitial cells in his detailed account of the male sex organs, Zur Anatomie der männlichen Geschlechtsorgane und Analdrüsen der Säugetiere, published in 1850:

«The comparative studies of the testis resulted in the discovery of cells surrounding the seminiferous tubules, vessels, and nerves. These special cells are present in small numbers where they follow the course of the blood vessels, but increase in mass considerably when surrounding seminiferous tubules. These cells are lipoid in character; they can be colourless or can be stained yellowish, and they have light vesicular nuclei.»

This description indicates clearly that Leydig recognized the specific morphology of these cells; their endocrine nature and ultrastructure have only recently been fully understood.

Leydig is also known for describing large vesicular cells that occur in the connective tissue and in the walls of blood vessels in crustaceans (1883). Four different types of the latter have been determined.

Leydig became professor of comparative anatomy at the University of Bonn in 1875. Here he was also director of the anatomical institute as well as director of the zoological museum and the zoological institute. He was later made Geheimer Medizinalrat.

Leydig was emerited on April 1, 1887, and retired to the town of his birth. He had married Katharina Jaeger, the daughter of a professor of surgery at Erlangen, who survived him; they had no children. During his lifetime, Leydig was granted many honours, including personal ennoblement, and an honorary doctorate of science from the University of Bologna. He was a member of a number of medical and scientific societies, among them the Royal Society of London, the Imperial Academy of Science of St. Petersburg, and the New York Academy of Sciences.

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