ROBERT IGBEDE

1. BY
ROBERT IGBEDE

2.  The pituitary gland or hypophysis hangs from
the hypothalamus by its neck called the
infundibulum and is located within in the
hypophyseal fossa (deepest part of sella
turcica) of the shenoid bone
 It is divided into an anterior lobe or adeno-
hypophysis and a posterior lobe or neuro-
hypophysis, both seperated by a thin lamina

3.  The neuro-hypophysis or posterior pituitary
gland is called neurohypophysis because is
derived from the neural crest during
embryonic development
 It is called posterior pituitary because it is
located posteriorly on the pituitary gland
 It is the smaller of the two lobes

5.  The PPG is highly vacularized. It has a
capillary system which is supplied by the
inferior hypophyseal artery
 It contains the nerve endings of the
neurons(magnocellular) that begin in the
hypothalamus
 This neurons have their soma embedded in the
paraventricular and supraoptic nuclei of the
hypothalamus
 Contains glial cells (pituicytes) that support
this neurons

6.  The posterior pituitary gland does not
synthesize or secrete any hormone itself.
 The hormones are synthesized in the soma of
the neurons in the hypothalamus and travels
within secretory vessicles by anterograde
transport to the axon which lies in the posterior
pituitary gland and is stored in the posterior
pituitary gland
 This migration of the secretory vesicle through
the axoplasm of the neuron is facilitated by a
carrier protein called neurophysin

8.  There are two hormones that are stored in the
posterior pituitary gland
 1) ADH (vasopressin): anti diuretic hormone is
synthesized primarily in the soma of the
supraoptic nuclei found in the hypothalamus
 2) Oxytocin: it is synthesized primarily in the
soma of paraventricular the nuclei