[Ependymal structures in the telecephalon of Salmo irideus (Teleostei)]

The ependyma in the region of the telencephalon of Salmo irideus is composed of a great number of various elements: uni- and bipolar tancytes, ependymal astrogliacytes, ciliated ependymal cells, intraependymal neurons and neuron-like cells exhibiting ventricular contact. There are regional differentiations in the ventricular wall which can be attributed to certain structurally defined nuclear areas. When comparing the various regions of the ventricular wall in the telencephalon of Salmo irideus with appropriate regions of amphibians and reptiles, some, at least partially, far-going morphological similarities can be found. The ependymal differntiations could, thus, be regarded as an additional morphological criterium concerning the question of the homologization of the telecephalic nuclear areas with those of other verebrates. The abundnat occurrence of tanycytes of the bipolar type in the telecephalon appeared surprising; they are discussed to act in a preponderantly resorptive manner, as it is, above all, hitherto known for hypothalamic regions of other vertebrates. The morphological and functional characteristics of the neuronlike structures exhibiting ventricular contact are as yet not clear.