"Computergestützte 4D-Rekonstruktion des Plattfischkopfes während der Metamorphose am Beispiel des Steinbutts (Psetta maxima, Linnaeus, 1758)"
Computer aided 4D-reconstruction of the flatfish head during metamorphosis in the turbot (Psetta maxima)
The metamorphosis of flatfishes is one of the most striking morphological events in the ontogeny of vertebrates. The animals change from a pelagic way of life with a bilateral symmetric body and a "normal" swimming posture to a benthic life permanently lying on onebody side. This requires the migration of the downward directed eye to the new upper body side and, entailed with this, more or less asymmetric deformations of other organ systems in the head region.
In this study the development of the left-eyed turbot (Psetta maxima, three selected larval stages) is investigated morphologically in detail. Using computer aided means of digital imaging, organ classification and 3D-reconstruction based on semithin section series the following organ systems of the head region can be displayed in free combination and perspective: integument with side channel system, chondro- and osteocranium, jaw muscles, brain, olfactory organ, eyes with optical nerve and eye muscles as well as the labyrinth organ with its sensory epithelia. This is complemented by scanning electron microscopy of the integument.
The virtual "fish from glas" in combination with the histological slices allows a detailed morphological and morphometrical description of complex relative organ positions and developmental processes in the turbot head (e.g. growth, more or less asymmetric changes of organ shapes and relative positions, degenerations etc.).
Most remarkable are the asymmetries of the retrorbital vesicles and of the integument still before the onset of eye migration, the resorption events in the chondral skeleton during eye migration, the persisting shape and orientation of the labyrinth organ despite the permanent side posture and the formation of a special bone only in the right half of the head.
The new image data are compared with previous findings published on flatfishes and discussed critically, last but not least in the sense of functional eco-morphology.