ИСТИНА

The aim is the reconstruction of the cerebral ganglion (= brain, Richter et al., 2010) fine structure for comparative analysis of Cestoda. The brain of [Parachristianella sp.] (Trypanorhyncha) consists of two pairs of frontal and lateral lobes and an unpaired central (=median) lobe. The frontal lobes are combined by the dorsal and ventral semiring commissures. The lateral lobes are connected by median and crisscross commissures. Dorsal and ventral rootlets originate from the lateral lobes to innervate bothria. Special features of the brain are: 1) an unpaired midline neuropil and compact neuropils in the frontal and lateral lobes; 2) three types of commissures; 3) the crisscross commissure with giant axons somata; 4) four pairs of nerves with myelinated-like giant axons. The brain of [Parachristianella sp.] contains 200 neurons and glial cells (Biserova, Korneva, 2011). For comparison, the brain of [Ligula intestinalis] plerocercoid (Diphyllobothriidae) consists of the frontal and lateral lobes connected by a massive median commissure, and the ventral azygos lobe, located ventrally of the commissure (Biserova, Gordeev, 2010). Two crossed ventral nerves originate from the unpaired ventral lobe. The brain of [L. intestinalis] possesses bilateral symmetry. In contrast, the brain of [Triaenophorus nodulosus] (Bothriocephalidea) has symmetrical lateral lobes connected by a long median commissure without any concentration of neurons (lack of median lobe), and with symmetrical dorsoventral rootlets to the bothria (Biserova et al., 1996). Thereby it has radial double-beam symmetry. A comparative analysis shows significant differences in brain structure between cestodes groups: three brain commissures and nine neuropils in compound brain of Trypanorhyncha and, in contrast, a single median commissure and two neuropiles of Diphyllobothriidae and Bothriocephalidea.