Kostiuk A. Morphofunctional features of the cloacal bursa in postnatal ontogenesis of domestic turkey

The dissertation work is dedicated to the research of morphofunctional features of the cloacal bursa in postnatal ontogenesis of domestic turkey. The complex research on macro- and microstructure of the cloacal bursa, cellular content and changes in postnatal ontogenesis of domestic turkey breed local bronze was conducted. The cloacal bursa registered in domestic turkey from one to 330 days. In older birds bursa is absent. Up to 240-days of age the organ is shaped like a spherical or elongated, flattened dorsoventraly bag with loose consistency. In older birds it becomes stick like or hook like with a pointed end and side-cranial invaginations with dense consistency. 23 It is shown that the growth of cloacal bursa in domestic turkey ends at 210–240-days of age. Changes of its morphometric parameters occur in three stages: intensive increase (from one to 60 days), moderate increase (from 60 to 210–240 days) and decrease (from 240 to 330 days). It is proved that the maximum morphofunctional parameters of domestic turkey’s cloacal bursa, as the central organ of hematopoiesis and immunogenesis, registered in a 180-days. In this age lobules bursales in cloacal bursa, providing this function, occupy the largest area. It was established that mucous membrane of cloacal bursa in domestic turkey contains lymphoid tissue, which is characteristic for peripheral organs of immunogenesis. Its level of structural organization varies in certain age of birds. The mucous membrane of cloacal bursa in domestic turkey contains lymphoblasts, prolymphocytes, large, medium and small lymphocytes, plasmacells, macrophages, epithelial cells (stellate epithelial cells and surface epithelium) heterophils and fibroblasts. It is shown that the largest population of cloacal bursa cells represented by lymphocytes. The content of other cells is negligible. The signs of cloacal bursa involution can be determined in domestic turkey in the 210-days of age. It appears with macroscopic and microscopic features. Macroscopic signs of involution of the cloacal bursa are manifested by absolute reduction of weight and size, and changes in texture and shape. Microscopic features characterized by vacuole degeneration of the surface epithelium, loss of folding, cysts and delymphatization of lobules and organ replacement by parenchymal and stromal structures of dense fibrous connective tissue in males and in females – mostly by fatty tissue.