MICROSCOPIC STRUCTURE AND MORPHOMETRIC PARAMETERS OF EUROPEAN CATFISH (SILURIS GLANIS L.) SPLEEN

Purpose. Study of the microscopic structure and morphometric parameters of European catfish spleen. Methodology. For the study, we used the spleen of clinically healthy age-2 European catfish (Silurus glanis L.). We determined the absolute and relative weight of the organ or the index of spleen development. For the histological studies, pieces of the material were preserved in 10-12 % cooled neutral formalin solution, with subsequent filling in paraffin. Paraffin sections were prepared using a sledge microtome, with a thickness of no more than 10 microns. To determine the cell and tissue morphology under light microscopy, we the staining of histological sections with hematoxylin and eosin. Determination of spleen linear dimensions, morphometric measurements were carried out using the "Master of Morphology". Quantitative parameters were analyzed in "Statistica 6.0". Findings. European catfish spleen corresponded to general regularities of fish spleen structure: we identified support-contractile apparatus, white and red pulp and inherent cellular composition. Peculiarities of the microscopic structure of this organ in European catfish is underdevelopment of radial trabeculae, poor development of periarterial lymphoid sheaths, absence of the differentiation to zones in lymphoid nodules. The most developed was red pulp (70.82 ± 10.76%), the least developed ? support-contractile apparatus (7.04 ± 0.65%). The base of the white pulp (22.14 ± 6.61%) is lymphoid nodules without propagation center. The support-contractile apparatus of the spleen, which includes capsule and trabecular system, is developed unevenly. E.g., the capsule thickness in different parts of the body is not the same, the biggest thickness is in porta, where it attains 21.85 ± 7.44 micrometers, its relative area is 3.06 ± 0.32%. Relative area of the trabecular system is 3.98 ± 2.57%, the most developed are vascular trabeculae. Originality. We found the peculiarities of spleen structure of European catfish and performed a morphometric analysis of the structural components of this organ: the ratio of white to red pulp is 1: 3.2; support-contractile apparatus to parenchyma ? 1: 13.2, the relative weight is 0.086 ± 0.0006%. Practical value. The determination of morphometric parameters of European catfish spleen as a hemopoietic organ and immune protection organ is necessary for the industrial cultivation of healthy fish. Detection of their changes, especially such parameters as relative weight and relative area of white pulp, can be used for the identification of negative factors, monitoring of water systems and creation of favorable conditions for aquatic organisms.