POST-HATCH DEVELOPMENT OF PREEN GLAND IN THE DUCK {Anas platyrhynchos)
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Date
2005
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR
Abstract
Studies on the post-hatch development of the preen gland in ducks were
conducted using 44 ducks from the day of hatch till 150 days of age. The project
was taken up to trace the structure and development of the glands and their
relationship with the age and body weight.
After recording gross relations and measurements, the material was fixed
using various fixatives for studying the cellular details, arrangement of cells,
connective tissue framework, micrometry and histochemistry.
The preen gland was a paired organ with a common cylindrical papilla.
The two glands together formed a 'V shaped structure. Each gland was pear
shaped and pale yellow in colour, in fresh state. They were located on the dorsal
surface of the pygostyle. Both the right and left glands had separate ducts. The
uropygial circlet was seen at the tip of the papilla. The glands were vascularized
through a pair of branches from the caudal artery and innnervated through the
medial caudal nerve. The weight of the preen glands increased progressively
from the day of hatch to 150 days of age. This weight was positively correlated
with the age and body weight. The proportion of the gland weight to the body
weight showed a decreasing trend. The right gland was slightly heavier, longer,
wider and thicker than the left. The length, breadth and thickness were
positively correlated with the age and body weight.
Structurally, the glands were simple, branched, tubular and holocrine
type. The richly vascularised connective tissue capsule was eomposed of
collagen and reticular fibres. Elastic and smooth muscle fibres were absent. The
secretory tubules showed two zones, an outer zone or zone I, near the capsule
and an inner zone or zone II, towards the primary cavity. The epithelium of the
tubules consisted of basal, intermediate and transitional layers.
The papilla had two ducts, which were lined by glandular epithelium
initially and keratinized stratified stratified squamous epithelium at the tip. The
glandular epithelium was surrounded by longitudinally arranged smooth muscle
fibres and skin. Lamellar corpuscles and circlet feather follicles were noticed in
the papilla.
Capsule, trabeculae and the parenchyma were PAS positive. Glycogen
and acid mucopolysaccharides were not detected. Lipids were evident uniformly
in all the cell layers. The acid phosphatase activity was moderate in the basal
and intermediate layers and strong in the transitional layer. The alkaline
phosphatase activity was moderate in the basal and intermediate layers and weak
in transitional layer of outer zone. It was moderate in the basal and intermediate
layers and intense in the transitional layer of inner zone.
Statistical analysis showed a significant increase in the thickness of
capsule, width of the two zones and the primary cavity with the advance of age.
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