Imaging in Whale Fetuses: Ultrasonography and Computed Tomography in Different Cetacean Species of the Famous Historic Collection of Willy Kuekenthal
Willy Kuekenthal (1861–1922) was a German zoologist, a disciple of Ernst Haeckel, director of the museum of natural history in Berlin. Kuekenthal’s research concentrated on whale species. He was the founder of the Handbook for Zoology. With his studies, he confirmed the biogenetic law of Haeckel (1834–1919; From 1862–1909 Haeckel was professor and director of the zoological institute of the University of Jena and probably the most well-known German zoologist of his time, for his renowned works on the systematics of radiolarians, medusae and sponges, which he himself beautifully illustrated [Kunstformen der Natur, 1899–1904] and for his Biogenetic Law and the Gastraea theory; he coined the zoological terms “gastrula” and “coelom”).
The collection of Willy Kuekenthal is a very famous historic compilation of cetacean fetuses. We had the opportunity to examine fetal specimens of several species of Odontoceti (toothed whales) and Mysticeti (baleen whales) including the largest recent animal, the blue whale, two species of the highly intelligent and communicative dolphins, the tusked narwhal, the sperm whale, and the humpback whale; a representative selection out of the nearly 80 living species. We were delighted getting access to this historic collection for applying modem imaging techniques such as high end ultrasonography and computed tomography, in these valuable specimens of the museum of natural history of Berlin. The Cetacea are one of the most distinctive and highly specialized orders of mammals. We were able to visualize in situ some specialized adaptations for their aquatic life, like the highly compressed neck vertebrae, the inner ear with its heavily ossified structures, the skeleton of the flipper shaped forelimbs, the greatly elongated anterior skull bones, and the nostrils, located on top of the head, forming the blowhole. With a special CT window we were able to visualize for the first time the upper respiratory tract within the head and performed a “virtual endoscopy” along this course. In some specimens of the baleen whales, the vestiges of the pelvis and the fetal teeth, lacking completely in the adult, could be imaged.
CT has proved to be an excellent technique for imaging various structures, organs and whole organ systems of the fetuses in situ. The implementation of ultrasonography was limited to special questions. The resolution of parts of the soft tissue was higher, so the ultrasonographic imaging technique was able to cover examinations of defined regions of interest of soft tissue. Both imaging techniques provide the advantage of nondestructive examination of rare and valuable museum material. The findings are compared to the findings and notations of Kuekenthal1 in his 1893 monograph.
1. Willy Kilkenthal 1893: Vergleichend-anatomische und entwicklungsgeschichtliche Untersuchungen an Walthieren. Denkschriften der medizinisch-naturwissenschaftlichen Gesellschaft zu Jena 30., Jena, Gustav Fischer.