Components

Hypophysis

• As in mammals, the hypophysis (pituitary) gland in chickens is fixed at the base of the brain, below the diencephalus
• It is encapsulated by the dura-mater.

Adenohypophysis
• Composed of distal and tuberal parts
• The intermediate part doesn't exist

Distal Part
• Divided into cephalic and caudal regions.
• Both regions contain cords of acidophilic and basophilic cells and groups of cromophobic cells.
• The acidophilic cells from the cephalic region are pale and those of the caudal zone are more darkly stained. Therefore the cephalic zone seems more basophilic and the caudal zone more acidophilic.
• The cellular cords of the primary zone are more closely grouped than those of the latter zone.
• Some parenchymatous cells from the distal part can arrange themselves around a lumen filled with colloid, especially in older birds.
• In this part of the hypophysis gland, cysts can also occur lined by ciliated and mucous cells.

Tuberal Part
• Encircles the infudibulum.
• Spreads out dorsally over the ventral surface of the brain for a short distance.

 

Epiphysis Gland

• The epiphysis gland(pineal gland, pineal body, epiphysis cerebri) is a small and conic body
• It is situated between the cerebral hemispheres and the cerebellum
• It is surrounded by a connective tissue
• Formed by a body and a narrow ventral peduncle that is fixed on the roof of the third ventricle.
• The glandular parenchyma is arranged in lobules, separated by thin septa of connective tissue.
• The lobules contain cells, mostly pinealocytes that form rosettes or follicles.

Thyroid

• The thyroid glands are composed of numerous follicles filled with colloid, as in mammals.
• However, the cells with similar functions to that of the parafollicular cells of mammals occur in the ultimobranquial bodies (instead of the thyroid glands) in chickens.

Parathyroid Glands

• They are each surrounded by a connective tissue capsule.
• The parenchyma is formed by irregular cords of main cells, separated by connective tissue and numerous sinusoids.

Adrenal Glands

• The adrenal glands are enclosed by a dense connective tissue capsule.
• Unlike the mammals, the parenchyma is not organized into distinct cortex and medulla. Instead it is formed by interposed cortical (intrarenal) and medullar (cromaphin) tissues.
• The cortical cells are arranged in irregular cords. These cells have a dark nucleus and seem columnar when the cords are sectioned longitudinally.
• The medullar tissue is formed by polygonal cells. They are larger than the cortical ones and have large round nuclei and a basophilic cytoplasm.
• Ganglionary cells appear between the medullar cells.
• Two ganglions (cranial and caudal suprarenal ganglions) are juxtaposed to the surface of the adrenal glands and are frequently included in histological sections of this gland.