The posterior pituitary also known as the neurohypophysis contains nerve endings of tracts that originate in the hypothalamus. The two "nuclei" that supply these tracts are the Paraventricular and Supraoptic. The primary secretion of the paraventricular nucleus is OXYTOCIN. The primary secretion of the supraoptic nucleus is ADH also known as Vasopressin. Even though these nuclei have a "primary" secretion, each nucleus can synthesize approximately 1/6th of the other hormone that is not it's primary secretion. The best way to remember is the acronym POSA(paraventricular-oxytocin/supraoptic...