Posterior 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.[2] The posterior pituitary consists mainly of neuronal projections (axons) of magnocellular neurosecretory cells extending from the supraoptic and paraventricular nuclei of the hypothalamus.In addition to axons, the posterior pituitary also contains pituicytes, specialized glial cells resembling astrocytes assisting in the storage and release of the hormones.It is based upon the gross anatomical separation of the posterior and anterior pituitary along the cystic remnants of Rathke's pouch, causing the pars intermedia to remain attached to the neurohypophysis.Insufficient secretion of vasopressin underlies diabetes insipidus, a condition in which the body loses the capacity to concentrate urine.