DEVELOPMENT AND FUNCTIONAL ORGANIZATION OF CENTRAL ORGANS OF BREAM (ABRAMIS BRAMA (L.)) LARVAE HEMATOPOIESIS

The article dwells upon physiological and morphological studies of fish carried out on a large scale, due to the need to control their reproduction and assess the impact of living conditions on the body of fish. Currently, a large amount of data on hematopoietic organs and the formation of blood cells in fish have been accumulated, but the facts are quite contradictory. At the same time, the state of the hematopoietic system can be justified only according to histogenesis of hematopoietic organs. From the results of examining reticular intercanal tissue of the head kidney (pronephros) of bream, a typical representative of bony fish, it can be inferred that pronephros is one of the main hemopoietic organs, in which the process of developing red blood cells and leukocytes takes place, with the majority of cells accounted for blood cells of erythropoietic series. Pronephros loses its excretory function in the early stages of ontogenesis. Throughout its development pronephros is presented as a dense formation, in the intercanal tissue of which there is reticular tissue with numerous hematopoietic elements. Active hematopoiesis occurs in mesonephros (trunk kidney) of bream larvae. The study of the morphophysiology of mesonephros in ontogenesis showed that this organ forms blood elements of all series, with more than half of the hematopoietic elements accounted for erythropoietic cells. The excretory function of the trunk kidney is maintained throughout the whole period of the organ developing. Thus, mesonephros of bream is also one of the main organs of hematopoiesis represented by a paired organ which stretches along the spine.