A Comparative Morphological Observations on the Preen (Uropygial) Glands of Geese, Ducks and Young Pigeons

The uropygial gland in birds; is an organ located on the back near the base of the tail. It is more important for aquatic birds, but why it is so important for other birds? and what is the nature of its secretion?
       Twenty  male  domestic  geese (Anser anser domesticus )of one year old , twenty male  Muscovy ducks (Black Magpie)of one year old  and twenty five male young  pigeons (Columba livia domestica) of 6 weeks old  were used through this study.
        The results indicated that in ducks and geese the gland secretes glycolipids, but only oily secretion. in young pigeons. According to mode of secretion, the glands of all 3 species were of holocrine mode of secretion in young pigeons there was a central lumen leading to one excretory duct opening on a small papilla for each of the two lobes which are not divergent. In ducks and geese, the two lobes were diverged, each having one collecting sinus leading to one excretory duct for each lobe opening on a small papilla in ducks but it was broader in geese. The capsule of the gland was thicker in geese and ducks but the least in young pigeons.
        The cells of the secretory tubules are arranged in 4 zones for the three species. The secretory cells had more characteristic cells in geese than in ducks. The mast cells were more evinced in ducks and geese but were fewer in young pigeons. The average glandular weight was in geese 8.50 +0.22 gm for 3 Kg body weight, lesser in ducks, 7.00 +0.20 gm for 3 Kg body weight   but the least in young pigeons (0.27+ 0.02gm) for 350 gm body weight.      
       The tissues stain ability for lipids by oil red O was at the same degree in the three studied species.