Posterior pituitary Posterior pituitary The posterior pituitary (or neurohypophysis) is the posterior lobe of the pituitary gland which is part of the endocrine system. The posterior pituitary is not glandular as is the anterior pituitary. Instead, it is largely a collection of axonal projections from the hypothalamus that terminate behind the anterior pituitary, and serve as a site for the secretion of neurohypophysial hormones (oxytocin and vasopressin) directly into the blood. The hypothalamic–neurohypophyseal system is composed of the hypothalamus (the paraventricular nucleus and supraoptic nucleus), posterior pituitary, and these axonal projections. The posterior pituitary consists mainly of neuronal projections (axons) of magnocellular
Pituitary adenoma interacting protein" ("AIP") gene , and duplications in chromosome Xq26.3 that include the "GPR101" gene that also causes X-linked acrogigantism (X-LAG) syndrome. About 15-20% of FIPA families carry a germline "AIP" gene mutation or deletion, and the disease occurs as autosomal dominant with incomplete penetrance, meaning that about 20% of AIP mutation carriers will develop a pituitary adenoma. "AIP" mutation associated pituitary adenomas (either presenting as FIPA or as individual, non familial cases) are usually growth hormone secreting (acromegaly) or prolactin secreting (prolactinoma) adenomas that are large (macroadenomas) and often occur in children, adolescents and young adults. Daly and colleagues