The Hypothalamus and Posterior Pituitary Two major hypothalamic nuclei – the supraoptic and paraventricular nuclei – synthesise the peptides vasopressin and oxytocin (Fig. 5.2). Each neurone in these nuclei synthesises either oxytocin or vasopressin as part of a larger precursor molecule. After packaging, the peptides are transported as granules, by axoplasmic flow, to the nerve terminals in the posterior pituitary where they are released directly into the circulation to act as classical neurohormones on distant target sites. See later: • Distribution of Neurones • Neuronal Tracts • Sensory Tracts