BERNSTEIN, P.; University of Tuebingen: The Inner Ear Anatomy of the Coelacanth Revealed by High-Resolution X-Ray CT

High resolution computed tomography (CT) was used to investigate the otical region of an adult specimen of Latimeria chalumnae. In earlier studies a complicated composition of the coelacanth�s inner ear has been described, with a confusing arrangement of endo- and perilymphatic ducts, partly combining both inner ears and the labyrinths with the endocranial cavity. The CT data were used in combination with 3-D-software to create a three-dimensional digital reconstruction of the otical region.
For this study an industrial CT scanner was used allowing for much higher resolution than conventional medical CT devices. Thus it was possible to show even very small structures otherwise only accessible by histological or dissection methods. Because the CT method is noninvasive (using x-ray technology) the material was not destroyed during the procedure.
Computed tomography gives information on different densities of the organisms� tissues and is particularly useful with respect to hard tissues i.e. bone and cartilage. Since the inner ear ducts are embedded in skeletal tissue the CT method was the most suitable noninvasive method. The results show the course of the duct between the inner ears (canalis communicans) and the tiny ducts leading from this canal to the endocranial cavity in great detail. The data confirm earlier results and make visible the three-dimensional course of these ducts for the first time.