Leydig, Franz von

(b. Rothenburg-ob-der-Tauber, Germany, 21 May 1821; d. Rothenburg-ob-der-Tauber, 13 April 1908),

comparative anatomy.

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 elder Leydig being a keen gardener and beekeeper. Leydig himself later recalled that these childhood interests established his lifelong concern with botary and zoology. At the age of twelve the boy acquired i simple microscope, at which he spent most of his free time. (A few years later, during his studies at Wurzburg, a local doctor lent him a more sophisticated instrument.)

Beginning in 1840 Leydig studied medicine at the universities of Würzburg and Munich. He received his doctorate in medicine at Würzburg and became an assistant in the department of physiology, teaching also histology and developmental anatomy under Kölliker. He qualified as a university lecturer in 1849, and as extraordinary professor in 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 at the University of Tübingen and published his Lehrbuch der Histologie des Mensehen 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 Purkyně, Valentin, and Schwann, the last of whom described it as a vesicle containing a nucleus (1839). Leydig paid further tribute to other contemporary anatomists, particularly Johannes Müller 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 Gerlach’s 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 larval Amphibia. This mucous cell is peculiar in that it does not pour its secretions 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 occurs in the seminiferous tubules and in the mediaseptum and connective-tissue septa of thc testes. These cells are believed to produce the male hormone testosterone, which determines mule 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 die seminiferous tubules, vessels, and nerves. These special cell? aie present in small numbers Where they follow the course of the blood vessels, but Increase in mass considerably when surrounding seminiferous tubules. These cells arc lipoid in character; they can be colorless or can be stained yellowish, and they have light vesicular nuclei [p. 47].

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 the discovery of the gland of Leydig (1892), a portion of the mesonephros in vertebrates, of which the secretions are thought to stimulate the movement of spermatozoa; and 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. He was made emeritus in 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 honors, 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.

BIBLIOGRAPHY

I. Original Works. Leydig’s most important writings include “Die Dotterfurchung nach ihrem Vorkommen in der Tierwelt und nach ihrer Bedeutung,” in Isis. Encyclopädische Zeitschrift, vorzüglich für Naturgeschichte, vergleichende Anatiomie and Physiologie von [Lorenz] Oken, pt. 3 (1848), cols. 161-193; “Zur Anatomie der männlichen Geschlechtsorgane und Analdrüsen der Säugetiere,” in Zeitschrift für wissenschaftliche Zoologie, 2 (1850), 1-57; “Über Flimmerbewegung in den Uterindrüsen des Schweines,” in Archiv für Anatomie, Physiologie und wissenschaftliche Medicin (1852), 375-378; Beiträge zur mikroskopischen Anatomie und Entwicklungsgeschichte der Rochen und Haie (Leipzig, 1852); “Zum feinen Aufbau der Arthropoden,” in Archiv für Anatomie, Physiologie und wissenschaftliche Medicin (1855), 376-480; “Über Tastkörperchen und Muskelstruktur,” ibid. (1856), 150-159; Lehrbuch der Histologie des Menschen und der Tiere (Frankfurt, 1857); “Über das Nervensystem der Anneliden,” in Archiv für Anatomie und Physiologie (1862), 90-124; “Neue Beiträge zur anatonischen Kenntnis der Hautdecke und Hautsinnesorgane der Fische,” in Festschrift zur Feier der 100jährigen Bestehens der Naturforschenden Gesellschaft zu Halle (Halle, 1879), 129-186; Zelle und Gewebe. Neue Beiträge zur Histologie des Tierkörpers (Frankfurt, 1885); “Die riesigen Nervenröhren im Bauchmark der Ringelwürmer,” in Zoologischer Anzeiger, 9 (1886), 591-597; “Das Parietalorgan der Wirbeltiere. Bemerkungen,” ibid, 10 (1887), 534-539; “Nervenkörperchen in der Haut der Fische,” ibid, 11 (1888), 40-44; “Das Parietalorgan der Reptilien und Amphibien kein Sinnesorgan,” in Biologisches Zentralblatt, 8 , no. 23 (1889), 707-718; “Besteht eine Beziehung zwischen Hautsinnesorganen und Haaren?,” ibid, 13 , nos. 11-12 (1893), 359-375; “Zur Kenntnis der Zirbel- und Parietalorgane. Forgesetze Studien,” in Abhandlungen hrsg. von der Senckenbergischen naturforschenden Gesellschaft, pt. 3 (1896), 217-278; “Der reizleitende Theil des Nervengewebes,” in Archiv für Anatomie und PhysiologieAnatomische Abt. (1897), 431-464; “Zirbel und Jacobson’sche Organe einiger Reptilien,” in Archiv für mikroskopische Anatomie und Entwicklungsmechanik, 50 (1897), 385-418; and “Bemerkung zu den ‘Leuchtorganen’ der Selachier,” in Anatomischer Anzeiger, 22, nos, 14-15 (1902), 297-301.

II. Secondary Literature Obituary notices are O. Boettger, in Zoologischer Beobachter50, no. 1 (1909), 31; R. von Hanstein, in Naturwissenschaftliche Rundschau, 23, no. 27 (1908), 347-351; M. Nussbaum, in Anatomischer Anzeiger, 32, nos. 19-20 (1908), 503-506; and in Kölnische Zeitung, no. 520 (14 May 1908); O. Schultze, in Münchener medizinische Wochenshrift, 55, no. 18 (1908), 972-973; O. Taschenberg, in Leopoldina, pt, 45 (1909), 82-88; and O. Zacharias, in Archiv für Hydrabiologie, 4, pt. 1 (1908), 77-82.

P. Glees