Gross anatomy and histological features of Pituitary Gland

What is pituitary gland?
Also known as hypophysis cerebri, pituitary is an ovoid neuroglandular organ.
It is suspended from the floor of the third ventricle by a stalk known as infundibulum.
It is located in a depression called hypophyseal fossa of sella turcica of body of sphenoid. The fossa is roofed by the diaphragm sellae which is a fold derived from the meningeal layer of dura mater. The diaphragm sellae is pierced by the pituitary stalk or infuldibulum.

What are the presenting parts?
The gland consists of:
An anterior lobe or adeno-hypophysis and
A posterior lobe or neurohypophysis

Gross anatomy of Anterior Lobe or adeno-hypophysis:
It is highly cellular and occasionally presents intra-glandular cleft. The part behind the cleft is known as pars intermedia, which is rudimentary in human beings and embraces the front and sides of the posterior lobe. The part of the anterior lobe extending upward along the infudibular stem is known as pars tuberallis. The rest of the gland in front of the cleft is called pars anterior or pars distalis.

Gross Anatomy of posterior lobe or neurohypophysis:
It is continuous above with the infundibulum. It consists of three parts:
Median eminence of tuber cinerium, infundibular stem and pars nervosa


Anteriorly: anterior intercavernous sinus
Posteriorly: posterior intercavernous sinus, dorsum sellae, the basilar artery, and the pons
Superiorly: optic chiasma, anterior communicating artery and the floor of third ventricle separated by the diaphragma sellae, which has a central aperture that allows the passage of the infundibulum
Inferiorly: The body of the sphenoid, with its sphenoid air sinuses
On each side: The cavernous sinus and its contents

Arterial Supply:

Anterior lobe:
by superior hypophyseal artery (branch of internal carotid artery)
Breaks up and form capillary plexus in the median eminence and infundibular stem
Long and short portal vessels arise from these plexus and supply the anterior lobe
Posterior lobe:
by inferior hypophyseal artery (branch of internal carotid artery)
Enters the posterior lobe and form capillary plexus to supply it.

Venous Drainage:
Small veins arise from the surface of the gland and drain into neighboring dural sinuses

What is the structure or histological features of Pituitary gland?
Pars anterior: consists of
          chromophil cells and chromophobe cells

Chromophil cells are classified into
          Acidophil cells (secrete somatotrophs, mammotrophs)
          basophil cells (secrete corticotrophs, thyrotrophs, gonadotrophs)

Chromophobe cells: they contain very few granules in the cytoplasm

Pars tuberalis: consists of mainly undifferentiated cells and some acidophil and basophil cells

Pars intermedia: it is poorly developed in human.

Pars posterior:
          unmyelinated nerve fibres with supporting cells called pituicytes
          stores and releases vasopressin (anti-diuretic hormone; ADH) and oxytocin

Following resources are used while preparing this post (readers are strongly recommended to go through them for more details):
Gray's Anatomy
K. L. Moore's Clinically Oriented Anatomy
R. Snell's Clinical Anatomy
Wheater's Functional Histology: A Text and Color Atlas
Junqueira's Basic Histology: Text and Atlas