Anterior pituitary develops from

The anterior and intermediate pas of pituitary develop from an ectodermal diveiculum that grows upwards from the roof of stomatodaeum, just in front of the buccopharyngeal membrane called Rathke's pouch. Rathke's pouch appears in the third week of intrauterine life. Posterior pituitary develops from a downgrowth from the floor of third ventricle. This down growth fuses with the posterior aspect of Rathke's pouch. Craniopharyngiomas are peculiar tumours that arise from the remnants of this pouch. (Ref: human embryology by IB Singh, 9the edition, pg-310)