Dimensions of the vestibular and tympanic scalae of the cochlea in selected mammals.
The spiral shaped organ of hearing occurs only in mammals. This shape creates good conditions for the acoustic wave inside the cochlea. There are various forms of the cochlea in different species of mammal: the number of turns ranges from 1.5 to 4.5, a fact for which there seems no obvious explanation. In order to become more familiar with the geometry of the cochlear scalae in animals, a microanatomical study was carried out on 40 temporal bones, obtained from four common species of mammal: cat, dog, cattle and macaca. The bones were dissected with the aid of an operation microscope using standard otosurgical equipment, in which their perilymphatic spaces were filled with latex and further prepared in a formalin stain. Each of the rubber molds was removed from the osseous matrix and subsequently manually cut into 1 mm segments. The results, presented in diagrams, indicate that the vestibular and tympanic scalae present alternate dominance in their width and height, as was previously found in a study of humans. The change of this alternation domination appears two to five times on their entire length. The dimensions of the cochlear scalae are to a certain extent proportional to the weight of the animal: the largest were found in cattle and the smallest in the macaca.
Wysocki
J
J
Department of Normal Anatomy, University Medical School in Warsaw, Poland. clintrial.fiedor@il.waw.pl
D000818:Animals; D002415:Cats / Q000033:anatomy & histology*; D002417:Cattle / Q000033:anatomy & histology*; D004285:Dogs / Q000033:anatomy & histology*; D008253:Macaca mulatta / Q000033:anatomy & histology*; D008953:Models, Anatomic; D012533:Scala Tympani / Q000033:anatomy & histology*; D014722:Vestibule, Labyrinth / Q000033:anatomy & histology*