Morphological parameters of the vertebral column in the rainbow trout (Oncorhynchus mykiss) (Teleostei, Salmoniform).

Morphological parameters of the vertebral column in the rainbow trout (Onco rhynchus mykiss) (Teleostei, Salmoniform). The biometrical study of length, height and width of the successive vertebrae constituting the vertebral ax is of the rainbow trout (Oncorhynchus mykiss) allows characteristic-looking vertebral profiles to be drawn. This study shows that the classical anatom ical division of the vertebral column into two regions (truncal and caudal) is morphologically unrealistic; it is better represented by a zonation in three parts: a postcephalic region (or antero-truncal region) composed of 8 to 10 vertebrae the first two of which make a peculiar "couple"; a middle region integrating the following truncal vertebrae and the 18 to 20 first c audal ones; and finally a ural region (or postero-caudal region). This morp hological zonation of the rachis is probably the functional result of the m ajor role played by the vertebrae in transmitting the propulsive forces of the trunco-caudal muscles to the snout tip during the subcarangiform swimmi ng in the rainbow trout. (C) 1999 Editions scientifiques et medicales Elsev ier SAS.