Morphological changes in the spleen structure of spawning omul infected with D. dendriticum

Morphological features of the structure of the spleen of spawning omul, infected with Diphyllobothriumdendriticum at plerocercoid stage, were studied, depending on the degree of invasion of the wall of the digestive tract. The object of the study was sexually mature omul specimens obtained in the Maloe Kolesovo area of Kaban district of the Republic of Buryatia according to the quota of the Baikal branch of the FSBRI ARSRIFO (as part of the resource research plan for 2019). During the study morphometric indicators of the internal structure of omul spleen, not invaded by plerocercoids and their changes with varying degrees of invasiveness were revealed. The total number of individuals for analysis was 17 heads, two of which were healthy, the rest were with different degrees of helminth infection. After weighing and measuring linear dimensions of the body of the fish, the blood was taken from the caudal artery. The degree of invasion was determined by counting plerocercoids on the intestinal walls. In uninfected omul specimens, classical morphological picture of the spleen was observed, with microscopy in white and red pulp, significant hemosiderin content was noted. With a low degree of omul invasion, structural changes in spleen tissues were noted with a decrease in hemosiderin content, characterized by the disorder of microcirculation: vascular lumen widened, venous blood filling, stasis and small focal hemorrhages. An uneven tuberous capsule and expansion of the subcapsular trabeculae were observed. Omul spleen tissues with a high degree of invasion of the abdominal cavity acquired a mosaic structure with the signs of hyperplasia and chronic plethora. Not large areas of pulp were observed with inhibited reproduction centers and sharply expanded central arteries, indicating changes in the immune status.