Catatan

The pituitary gland is formed of anterior (adenohypophysis) and posterior (neurohy-
pophysis) parts, which are embryologically derived from two different sources (1). The

primordium of the anterior pituitary, Rathke’s pouch, forms by the upward invagination

of the stomodeal ectoderm in the region of contact with the neuroectoderm of the primor-
dium of the ventral hypothalamus (2). Rathke’s pouch can be identified by the third week

of pregnancy (3). The posterior pituitary arises from the neural ectoderm of the forebrain.
The anterior pituitary is formed of three parts; the pars distalis (pars anterior or
anterior lobe), the pars intermedia (intermediate lobe), and the pars tuberalis (pars
infundibularis or pars proximalis), and forms 80% of the pituitary gland. In humans, the
pars distalis is the largest part of the anterior pituitary and is where most of the anterior
pituitary hormones are produced (3). The intermediate lobe is poorly developed in
humans and although it is only a rudimentary vestige in adults, it is relatively obvious
in pregnant women and in the fetus (4). The upward extension of the pars distalis onto

the pituitary stalk forms the pars tuberalis, which may contain a small number of gona-
dotropin-producing cells (3).