THE MORPHOLOGY OF THE URETER IN THE DUCK (ANAS-PLATYRHYNCHOS)

The morphology of the ureter of the duck was investigated, using histo logical, SEM and TEM techniques. The inner perimeter, the total thickn ess of the ureteral wall and the thickness of each uretral layer were measured. The epithelium was tall columnar and pseudostratified along all the tracts of the ureter and showed a high muco-secretive activity . The lamina propria contained numerous capillaries and aggregates of leucocytes and macrophages. Throughout the lamina propria there was a dense plexus of nerves. Some denuded single nerve fibres were observed between the epithelial basal cells. A plexus of nerves was also obser ved in the tunica muscularis. The ostium cloacale ureteris opened on a well-developed papilla in the dorsal region of the urodeum. The total thickness of the ureteral wall, the thickness of the lamina propria a nd the tunica muscularis, and the inner perimeter progressively increa sed towards the ostium. The above observations suggest that the avian ureter plays an important role in the modification of the urine coming from medullary cones, and in emission of the urine into the cloaca.