TY  - JOUR
A1  - Rauschmann, Michael A.
A1  - Huggenberger, Stefan
A1  - Kossatz, Lars Swen
A1  - Oelschläger, Helmut H. A.
T1  - Head morphology in perinatal dolphins: A window into phylogeny and ontogeny
JF  - Journal of morphology
N2  - In this paper on the ontogenesis and evolutionary biology of odontocete cetaceans (toothed whales), we investigate the head morphology of three perinatal pantropical spotted dolphins (Stenella attenuata) with the following methods: computer-assisted tomography, magnetic resonance imaging, conventional X-ray imaging, cryo-sectioning as well as gross dissection. Comparison of these anatomical methods reveals that for a complete structural analysis, a combination of modern imaging techniques and conventional morphological methods is needed. In addition to the perinatal dolphins, we include series of microslides of fetal odontocetes (S. attenuata, common dolphin Delphinus delphis, narwhal Monodon monoceros). In contrast to other mammals, newborn cetaceans represent an extremely precocial state of development correlated to the fact that they have to swim and surface immediately after birth. Accordingly, the morphology of the perinatal dolphin head is very similar to that of the adult. Comparison with early fetal stages of dolphins shows that the ontogenetic change from the general mammalian bauplan to cetacean organization was characterized by profound morphological transformations of the relevant organ systems and roughly seems to parallel the phylogenetic transition. from terrestrial ancestors to modern odontocetes.
KW  - pantropical spotted dolphin
KW  - Stenella attenuata
KW  - comparative head morphology
KW  - ontogenesis
KW  - phylogenesis
Y1  - 2006
U6  - https://doi.org/10.1002/jmor.10477
SN  - 0362-2525
SN  - 1097-4687
VL  - 267
IS  - 11
SP  - 1295
EP  - 1315
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Huggenberger, Stefan
A1  - Ridgway, Sam H.
A1  - Oelschlager, Helmut H.A.
A1  - Kirschenbauer, Irmgard
A1  - Vogl, Thomas J.
A1  - Klima, Milan
T1  - Histological analysis of the nasal roof cartilage in a neonate sperm whale (Physeter macrocephalus : Mammalia, Odontoceti)
N2  - The nasal roof cartilage of a neonate sperm whale (Physeter macrocephalus) was examined by gross dissection and routine histology. This cartilage is part of the embryonic Tectum nasi and is a critical feature in the formation of the massive sperm whale forehead. In neonates as well as in adults, the blade-like nasal roof cartilage extends diagonally through the huge nasal complex from the bony nares to the blowhole on the left side of the rostral apex of the head. It accompanies the left nasal passage along its entire length, which may reach several meters in adult males. The tissue of the nasal roof cartilage in the neonate whale shows an intermediate state of development. For example, in embryos and fetuses, the nasal roof cartilage consists of hyaline cartilage, but in adult sperm whales, it also includes elastic fibers. In our neonate sperm whale, the nasal roof cartilage already consisted of adult-like elastic cartilage. In addition, the active or growing, layer of the perichondrium was relatively thick compared to that of fetuses, and a large number of straight, elastic fibers that were arranged perpendicularly to the long axis of the nasal roof cartilage were present. These neonatal features call be interpreted as characteristics of immature and growing cartilaginous tissue. An important function of the nasal roof cartilage may be the stabilization of the left nasal passage, which is embedded within the soft tissue of the nasal complex. The nasal roof cartilage with its elastic fibers may keep the nasal passage open and prevent its collapse from Bernoulli forces during inhalation. Additionally, the intrinsic tension of the massive nasal musculature may be a source of compression on the nasal roof cartilage and could explain its hyaline character in the adult. In our neonate specimen, in contrast, the cartilaginous rostrum (i.e., mesorostral cartilage) consisted of hyaline cartilage with an ample blood supply. The cartilaginous rostrum does not change its histological characteristics during development, but its function In adults is still not understood.
Y1  - 2006
UR  - http://www.sciencedirect.com/science/journal/00445231
U6  - https://doi.org/10.1016/j.jcz.2006.01.001
SN  - 0044-5231
ER  -