Welcome to part VII of Hearing International’s series honoring the Cochlear Explorers. This week’s explorer is Ernst Reissner (1824-1878), a Baltic German anatomist from Riga, Livonia. Recall that there are many cells and other structures in the body named after the researchers who first described them. These are called Eponyms. The name of this week’s cochlear explorer, Reissner (prounced rīs′nĕr), is lent to Reissner’s membrane, a membrane inside the cochlea of the inner ear that Reissner was the first person to identify it.

Reissner’s Membrane

Reissner’s membrane, also called the vestibular membrane or the vestibular wall, separates scala media or cochlear duct from scala vestibuli. Together with the basilar membrane it creates a compartment in the cochlea filled with endolymph, which is important for the function of the organ of Corti. It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth.

Histologically, the membrane (marked by the arrow at the right) is composed of two layers of flattened epithelium, separated by a basal lamina. Its structure suggests that its function is a controlled transport of fluid and electrolytes into the cochlear duct (scala media).  The scala vestibule is filled with perilymph and the cochlear duct is filled with endolymph.  The process of forming the endolymph and the maintenance of the difference in ionic relationship composition between it and the perilymph is not yet completely understood. Reissner’s membrane (shown in photomicrograph at left) forms a selective barrier between the two fluids.

Ernst Reissner (1824-1878) followed Corti’s investigations with more refined techniques and largely confirmed Corti’s observations. However, he also added more details. Reissner felt that this partition consists of, in his words, “sehr zarten, structurlosen Lamelle, die mit Epithelialzellen … bekleidet ist ” (a very fragile, unstructured lamella, which is covered with epithelial cells). Since the membrane partitioned the canalis cochlearis  (cochlear duct) from the scala vestibuli, the membrane was later referred to as “vestibular membrane” until the structure received the Reissner eponym. The color engravings in Reissner’s thesis are esthetically quite appealing, but we find the plates in the subsequent publication..more informative – although Claudius [1856], a contemporary of Reissner, called the drawings “völlig unverständlich” (completely incomprehensible). 

According to Schacht and Hawkins (2004), the publication of his dissertation did not have the impact that Reissner had expected, and his observations failed to enter into the anatomical treatises of the cochlea. He therefore published a summary of his thesis work in the Archiv für Anatomie, Physiologie und Wissenschaftliche Medicin  [Reissner, 1854] in which he stated in frustration, “Da aber die später erschienenen Abhandlungen von dem betreffenden Gegenstande gar Nichts erwähnen, fühlte ich mich veranlasst, meine Beobachtungen aufs Neue vorzunehmen” (Since later treatises do not mention this object at all, I feel compelled to recheck my observations). 

The object he is referring to is the “Schneckenkanal”  (canalis cochlearis), the third partition in the cochlea that he discovered and added to the already known scala tympani and scala vestibule. Describing the borders of the Schneckenkanal, he notes that the separation of the endolymphatic canal from the scala vestibuli has apparently been completely overlooked up to this point.  Because it partitioned the canalis cochlearis from the scala vestibuli, the membrane was later referred to as “vestibular membrane” until it received the Reissner eponym. 

While Reissner is remembered for his anatomical studies of the ear and his discovery of the vestibular membrane that now bears his name; he is also remembered for his early research concerning the embryologic formation of the inner ear.  Reissner studied the formation of the inner ear initially using the embryos of fowls, then of mammals, mainly cows and pigs, and, to a lesser extent, human embryos.

The embryos were placed in water for maceration and fixed in vinegar or black wax. Black wax also provided contrast and supportive blocks to enable the cutting of thin sections. Only the surface of the specimens could be studied at this time since after staining they could not have been thin enough to gain in depth views. By sectioning embryos at different stages of development, Reissner was able not only to determine individual stages of the formation of the labyrinth and postulate its formation in man; but also to conclude that the web (the membrane) he noted in embryos is a permanent structure of the labyrinth in man.  From this research he was able to conceptualize formation of the labyrinth in humans.  Reissner also published diverse anatomical studies on the hair of humans and mammals, which his contemporaries considered as valuable as those on the ear.

.…..But Who WAS Reissner?

Ernst Reissner was born in the Latvian town of Riga….(then under Russian rule) in 1824, received a medical degree at the University of Dorpat in 1851 and became a Professor at Dorpat. Dorpat (now called the University of Tartu) was founded by the Swedish King Gustavus Adolphus in 1632 after the area had become part of the Swedish kingdom and is located in what is now Estonia. Although a Russian university at the time of Reissner (and Böttcher, a colleague at Dorpat), the language of instruction was German.   In 1857, he became Professor of Anatomy, a position that he held with great success until he retired in 1875.

For his years of distinguished work,  the imperial Russian government confirmed on him the honorary title and special rank within the Russian society of  Wirklicher Staatsrath (Real State Councillor).  He retired from teaching in 1875 for health reasons and died three years later, eight days before his 54th birthday.

Next Week learn about Hearing International for another Cochlear Explorer, Jean-Pierre Nuel