What are the two main parts of the pituitary gland and their origins?

The pituitary gland consists of two embryologically distinct parts: Adenohypophysis (anterior pituitary), which originates from ectoderm as Rathke’s pouch, and Neurohypophysis (posterior pituitary), derived from neuroectoderm of the hypothalamus.

How does the adenohypophysis develop from Rathke's pouch?

The adenohypophysis develops from the ectoderm of the primitive oral cavity as Rathke’s pouch, forming Pars anterior from the anterior wall, Pars intermedia from the posterior wall, and Pars tuberalis as an extension along the infundibular stalk. The hypophyseal cleft is the residual lumen between the anterior and intermediate parts.

What is the origin of the neurohypophysis?

The neurohypophysis originates from neuroectoderm in the floor of the third ventricle (hypothalamus), forming the pars nervosa (posterior lobe) and the infundibulum (stalk connecting to the hypothalamus).

What are craniopharyngiomas and how do they relate to pituitary development?

Craniopharyngiomas are tumors that arise from remnants of Rathke’s pouch, often located near the sphenoid bone and roof of the nasopharynx, due to incomplete development of the pituitary gland.

What are the main types of pituitary adenomas and their clinical presentations?

Pituitary adenomas are classified by cell type: Chromophobe adenoma is common in females aged 20–50, presenting with headache and bitemporal hemianopia. Acidophil adenoma causes gigantism in children and acromegaly in adults. Basophil adenoma leads to Cushing’s syndrome with fat redistribution in face, neck, and trunk.

What is accessory hypophyseal tissue and when does it occur?

Accessory hypophyseal tissue may form in the nasopharynx if the hypophysis fails to develop properly during embryogenesis, representing ectopic pituitary tissue.

Pituitary Development – Rathke’s Pouch & Infundibulum