— A comparative study into morphological features of the intraoral gustatory apparatus in juveniles of the common carp Cyprinus carpio and White Sea cod Gadus morhua marisalbi of the same age has been performed using scanning electron microscopy. Juveniles of these two fish species have a similar system of distribution of taste receptors in the oral cavity into three interrelated parts. The interaction between these parts provides a complex multistep system for taste analysis of food items. Features of morphology of the taste receptor apparatus in the same sensory zones of the oral cavity in juvenile common carp and cod show the similarity of their adaptation to the same type of feeding both on planktonic and benthic organisms. Species-specific features have been revealed in the morphology of the sensory field of taste buds. Some structural differences in morphology of the same sensory zones in the oral cavity of juvenile common carp and cod have an adaptive orientation due to species specificity of taste testing processes.

The morphology and distribution of taste buds in the outer integument of the body and in the oral cavity of two forms (blind cave and sighted terrestrial ones) of the astyanax Astyanax fasciatus and in intact and blinded individuals of the Buenos Aires tetra Hyphessobrycon anisitsi have been studied using electronic scanning and light microscopy. In sighted individuals of both species, the morphometric parameters of the taste apparatus and the distribution of taste receptors are similar; the taste apparatus in the oral cavity is more developed than in the outer covers. Morphologically different taste zones were found in the oral cavity of characins. In blind fish, the taste apparatus of the maxillary zones is distinguished by smaller taste buds and a greater density of their distribution. The sensory field of taste buds in blind and sighted individuals of astyanax and tetra has a similar ultrastructure; it is formed by taste cells of three types. In blind astyanaxes and blinded individuals of tetra, numerous modified epidermal cells were found for the first time in the epithelium of the taste zones and in contact with taste buds, which are regarded as tactile receptors and a constituent element of polysensory taste-tactile complexes localized in blind fish in mainly ventral sensory zones.

Методом электронной сканирующей микроскопии исследованы изменения в морфологии и ультраструктуре вкусового рецепторного аппарата в трёх отделах орофарингиальной полости у рыб (радужная форель Parasalmo mykiss) в условиях хронического выключения зрительной и обонятельной рецепции. Показано, что выключение как обонятельной, так и зрительной рецепции вызывает достоверные изменения в морфологии интраорального вкусового аппарата, сходные по интенсивности и динамике их проявления. В условиях хронической сенсорной депривации происходит активация роста вкусовых сосочков в слизистой выстилке сенсорных зон, иннерви-руемых ветвями лицевого и тройничного нервов. Одновременно во вкусовых почках челюстного и центрального отделов ротовой полости наблюдалась активация процессов морфогенеза вкусовых рецепторных элементов. В фарингиальном отделе, получающем иннервацию от языкоглоточного и блуждающего нервов, подобных изменений не обнаружено. Изменения в морфологии вкусового рецепторного аппарата ротовой полости, вызванные сенсорной депривацией, сохранялись на одном уровне в течение длительного времени (9 мес). Полученные данные указывают на существование у рыб хорошо развитых обонятельно-вкусовых и зрительно-вкусовых взаимодействий на уровне интраоральной вкусовой субсистемы.

Study of the structural organization of gustatory apparatus in rainbow trout Parasalmo mykiss performed using electron scanning microscopy demonstrated that external taste buds are absent in this species in skin covers of the head and in the circumoral region. In the oropharyngeal cavity (oral and gill cavities and pharynx) of the rainbow trout, a well-developed gustatory receptor apparatus was found. In correspondence with specific features of morphology and anatomy of the skull, taste buds form seven gustatory zones. Morphometric analysis demonstrated differences between gustatory zones in the pattern and density of distribution of taste buds, as well as in average sizes of their sensory field. Zones of similar innervation have many common features in morphology. Morphologically similar zones form three regions in the oropharyngeal cavity: rostral, central, and caudal. A tendency for a decrease in the concentration of taste buds in the rostrocaudal direction common for all sensory zones was revealed. The highest concentration of taste buds was recorded at papillae of rostral regions near big teeth. A typical feature of taste buds in rainbow trout is irregular shape of the taste pore. Analysis of ultrastructural specific features of apical processes of taste cells allows us to distinguish five cell shapes in the composition of taste buds. The numeric ratio of cell shapes varies in buds of different localization. The quantitative distribution of taste buds over sensory zones, specific features of morphology and sizes of their sensory field are discussed in relation to the feeding pattern of the species.

Investigation of the structure of the gustatory apparatus and morphometric features of the brain in two age groups (1.5 and 6 months) of Siberian sturgeon Acipenser baerii shows a well-developed gustatory system in all studied exemplars. In the oral cavity of the sturgeon, 14 sensory zones are separated, and eight zones are supplied by gustatory receptors. During the growth of the juveniles, morphometric parameters of the zones can change. The zones of the dorsal and ventral linings of the oral cavity are similar by morphology and size, and they are complementary. The largest zone of the oral cavity of the sturgeon with a complex structure is the palate organ. The taste buds of the sturgeon are characterized by a large variation in shapes of apical protrusions of receptor cells. Weight indices of the brain parts and estimated sensory coefficients show an increasing degree of development of the gustatory and olfactory systems during growth of the juveniles. Two age groups of the juveniles are characterized by similar morphometric parameters of the gustatory receptor apparatus with external localization, but the morphology of the gustatory apparatus of the oral cavity is different. The features of the gustatory system morphology are discussed in connection with biology of the species.

Особенности морфологии вкусового аппарата ротовой полости у беломорских наваги (Eleginus navaga L.) и трески (Gadus morhua marisalbi Der.) исследованы методами световой и электронной сканирующей микроскопии. Вкусовые рецепторы в ротовой полости обоих видов распределены по зонам, каждая из которых имеет определенную анатомическую локализацию, специфическую морфологию эпителиальной поверхности и объединяет морфологически однородное скопление вкусовых почек. Структура поверхности одноименных сенсорных зон сходна у трески и наваги. Оба вида тресковых рыб обладают в зоне мягкого нёба крупным скоплением вкусовых сосочков, которое подобно нёбному органу карповых рыб. Морфометрические параметры вкусового аппарата (размеры вкусовых почек, площадь их сенсорного поля и плотность их распределения) позволяют относить сенсорные зоны к трем отделам ротовой полости – челюстному, нёбному и глоточному. Зоны ротовой полости, расположенные на границах с внешней средой и с жаберной полостью, имеют высокую плотность распределения вкусовых почек. Максимальная концентрация вкусовых почек у наваги и трески отмечена в наружном эпителии губ. Высота вкусовых почек у обоих видов меньше толщины эпителия. Морфология сенсорного поля вкусовых почек сходна в одноименных зонах трески и наваги. Треска отличается от наваги крупными размерами сенсорного поля вкусовых почек во всех зонах ротовой полости. Морфологические особенности вкусового аппарата разных сенсорных зон рассматриваются как проявление их функциональной неоднородности.

At present, there are no simple and reliable methods for selection of compounds with physiological activity in super-low concentrations (SLC). The screening system with high predictability is proposed. At the beginning, experiment is carried out on infusorians--spirostoma. Their motion activity, behavior, living ability and shape are registered at concentrations of substances in a range of 10(-3)-10(-13) mol/l. If the effect is detected on spirostoma, then experiments are performed on laboratory animals or their isolated tissues. Specific deviations on injection substance in SLC are detected, depending on compounds class. Nine representatives of different classes of biologically active compounds are investigated in the work: carbofos, deltametrin, 3-quinuclidinyl benzylate, atropine, phenosan, fenazepam, dopamine receptor antagonist SCH-23390, ciprine, and hexenal. It is accepted that if compound action in SLC is observed on spirostoma, then effects in super-low doses are also detected in a whole animal.

The dynamics of the biochemical parameters of the external mucus of carp Cyprinus carpio L. exposed to 1 µM concentrations of heavy metal salts (CuSO45H2O, Pb(NO3)2 and ZnSO47H2O) were studied. The biochemical parameters of external mucus (specific weight, pH, total protein, hemoglobin, ketones) were measured during exposure at 1, 3, 6, 24 h and regularly during a 21-day post-exposure period. Significant changes in hemoglobin and total protein concentrations were determined during the period of exposure to heavy metals and after it. Correlations of changes in biochemical parameters of mucus with the intensity of some parameters of sun activity and radio radiation flow were found during the post-exposure period. It was concluded that it is necessary to assess the possible complex effects of various origin and the magnitude of environmental factors on fish.

The dynamics of the biochemical parameters of the external mucus of carp Cyprinus carpio L. exposed to 1 µM concentrations of heavy metal salts (CuSO45H2O, Pb(NO3)2 and ZnSO47H2O) were studied. The biochemical parameters of external mucus (specific weight, pH, total protein, hemoglobin, ketones) were measured during exposure at 1, 3, 6, 24 h and regularly during a 21-day post-exposure period. Significant changes in hemoglobin and total protein concentrations were determined during the period of exposure to heavy metals and after it. Correlations of changes in biochemical parameters of mucus with the intensity of some parameters of sun activity and radio radiation flow were found during the post-exposure period. It was concluded that it is necessary to assess the possible complex effects of various origin and the magnitude of environmental factors on fish.