"Rathke cleft cysts"
"The anterior wall of the pouch gives rise to the anterior lobe of the pituitary (pars distalis). The posterior wall of the pouch does not proliferate and remains as the intermediate lobe of the pituitary (pars intermedia). The lumen of the pouch narrows to form a cleft (Rathke cleft) that normally regresses. Persistence of this cleft with expansion is believed to be the origin of a Rathke cleft cyst (also known as pars intermedia cyst)."