[Outer nuclei of the diencephalon pretectal area of the sturgeons].

Cytoarchitectonics of outer nuclei of the pretectal area was studied in four species of the sturgeons: the great sturgeon Huso huso, L., the Russian sturgeon Acipenser güldenstädti persicus n. kurensis, Belyaeff, the starred sturgeon Ac. stellatus, Pall., and the barbel sturgeon Ac. nudiventris, Lov. Morphological organization of these structures was studied by methods of Nissl and Bielshowskii modified by Viktorov. In this part of the pretectal area, five nuclear structures were described: parvicellular and magnocellular outer pretectal nuclei, lamellar pretectal nucleus, and dorsal pretectal nucleus, as well as accessory optic nucleus. Comparison of the obtained results with literature data has revealed a sufficiently high level of differentiation of this pretectum part of the sturgeons. Besides, a general conclusion is presented on organization of their entire pretectal area.