Immunoperoxidase methods for the demonstration of leptin and S-100 protein were applied in routinefixed
paraffin sections on the uropygial gland of baladi duck. Intact uropygial glands from twenty adult
healthy duck were used after slaughter. The glands were removed then the tissue specimens were fixed
in 10% buffered neutral formalin. This study showed that the uropygial gland formed from two lobes,
which were encapsulated by a connective tissue capsule. Each lobe composed of peripheral tubules and
central tubules that separated by connective tissue septa. The epithelial cells of the secretory tubules
were consisted of four layers, the germinative, intermediate, secretory and degenerative cells.
Immunohistochemical examination revealed that the leptin immunoreactivity was distributed in both the
peripheral and the central tubules. The leptin immunostaining was strong in the basement membrane,
the cytoplasm of germinative cells, secretory cells and degenerative cells. In addition, strong reaction to
leptin antibody was seen in the lumen or central cavity of central tubules. Additionally, S100
immunoreactivity was detected strong in the capsule and with moderate reaction on the cytoplasm of
peripheral and central tubules. This study emphasized that the strong positive reaction to leptin
immunostaining in the secretion of central tubules reflect the nature of secretion of the preen wax. In
addition, the expression of S100 protein immunostaining may indicate specific functions.