الفهرس 
Anatomy of pituitary glandOnly 14 pages are availabe for public view
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Abstract
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SUMIIlARY
Pi tuitary gland
Pituitary gland is an exceedingly important ductless
gland with a wide range of functions including
the centnal, of other ductless glands and of body growth.
It is reddish grey ovoid body 12 x 8 mw. It is weight
is about 0.5 gram, heavier in ~ than t , it is situated
in the hypophyseal fossa of sphenoid bone· The hypophysis
cerebri consists of an anterior and posterior lobe. The
anterior lobe is derived from the ectoderm of the stomodeum,
while posterior lobe is derived from the floor of
the fore-brain. ’fheunfundibulum which is directed downwards
and forwards contains a funnel-shaped recess from
the cavity of the third ventricle and is surrounded by
an upward extension from the anterior lobe of the gland.
~he pituitary gland receives blood supply from the internal
carotid anteries and the arterial circle.
Histologically the pituitary gland is sUbdivided
into anterior lobe and posterior lobe. The anterior lobe
consists of three parts pars distales, pars tUberales
and pars intermedia, while posterior lobe consists of
pars nervosa and infundibulum.
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The anterior lobe consists of group of cells according
to hormone which they secrete and the staining characteristics
of each cell pars distalia consist of chromophil
cell (48%) and chromophyobe cells about 52%.
The anterior lobe of pituitary gland secretes several
tropic hormones:
1. Growth hormone (GH) which is necessary for the growth
of many tissues particularly the skeleton. It has Qnabolic
effect with nitrogen balance. It is secreted
1y eosinophilic cells.
2. Thyroid stimulating hormone (T.S.H.) which has two
action on the thyroid gland: (a) Increase the vasculariby
and growth of thyroid gland. (b) Metabolic
action by increasing the picking up of the thyroxine
and triiodothronine.
J. Adrenocorticotrophic hormone (ACTH): stimUlating the
zona fasciculata and zona reticularis of the suprarenal
gland stimulating the formation of the glycocorticoids
and the adrenal sex hormone.
4. Gonadtrophic hormones:
a- Follicle stimulating hormones (FSH).
b- Lukeinishinghormone. (LH) or interstitial cell
st~nulating hormones (ICSH) or chorionic G.T.
c. Prolactin hormone (LTH).
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Pos terior lobe:
Its function is the store of two hormones which
are mWlufactured by the hypothalmus particularly the
supraoptic and paraventricular nuclei and these hormones
are released when needed they are:-
a- Vasopressin or antidiuretic hormone (ADH) leads
to water retention by·acting on distal and collecting
tubules of the kidney.
b- Oxytocin causes uterine contraction during labour ap~
milk ejection when an infant is breast fed due to
suckling reflex.
Pathology of pitUitary gland. Thel pituitary tumours,
These constitute about 10% of all intracramial tumours.
The commonest form is the benign adenoma, carcinomas may
accaur-e , The large numbero:t pituitary ’J.’umorsare nonfunctioning
chromophobe adenomas pituitary tumors are of
special interest because of the important complications
of their parasellar rextension and their dramatic syndrome
of honflonal hypersec.retion • .hndenohypophysial tumours
are customarly classified according to the characteristics
of the secretory granules into chromophobe,
acidophil and basophil types, although more than one cell
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type may occur in an individual tumor. It is convenient
also to include craniopharngiomas in a discussion
of pituitar,y tumours despite their origin from cells.
unrelated to the pituitary. The clinical problems presented
by these tumours resemble those of chromophobe
adenomas.
Eosinophilic adenomas account for 10-14% of
pituitary tumours sex and age and distribution does
not differ. It is encapSUlated slow growing and relatively
good hormone procedures • The majority of 3TH
producing pituitary tumours are composed-of relatively
sparsely granulated eosinophils and a granular cells.
An excess of STH produces increased growth reSUlting
in g1guitism in childran ·or acromegaly in adult.
Easophilic adenomas ACTH secreting. Most of ACTH
secreting pituitary adenomas remains under hypothalamus
influence and the target organ hormone in SUfficient
quantity will suppress the tumour.
ACTH secretion also can be suppressed in patients
with bilateral adrenal hyperplasia and cUShin”g’s syndrome
with or without a pituitar,y tumours and suppression
tests will not separate these groups of patients.Cushing’s
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syndrome is due to anterior pituitary neoplasia in at
least 10% of cases. About one half of these patients
have evidence of the tumours before surgery Patients
with cushing’s syndrome of pituitary origin may have
increased pigmintation a situation :analogous to the
cutaneous melanosis in Addison’s disease.
Chromophobe adenomas.: These are the most common
type of pituitary tumours. Men and women are equal
affected age, any age, but predominated in the third,
fourth and fifth decades of lifo. fhose tumours lack
large secretory granules but often contain sparse fine
granulation with periodic acid scheff stain.
Other tumours such as TSH-secretory tumours,
prolactin-secreting tumours and pluriglandular adenomaaoa
La ,
fhe craniophargyngioma: It is solid mass that undergoes
cystic change proliferation of the superficial layers
result in Keratinization formation of epithelial pearls
and calcification. Craniopharygngiomas are well encapsulated.
It shows histological pattern of an embryonal
tooth and is most often topped by a fibreues cyst’
Lin.ed by squamous epithelial cells, it contain blood
pigment and histocytes.
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Posterior pituitary:
ADH. antidiaretic hormone (vasopressin) is an
octapeptide synthesized in the paraventricular and
supraoptic nuclei of the hypothala/llUs as a part of
a polypeptide carriers portion (neurophysin D).This
prohormone cOlllpleJmigrates to posterior pituitary
where dissociation and simultaneous ~ecretion of the
neurophysin and ADH take ’place. ADH binds to receptors
in the distal convoluted tubules and collecting ducts
of the kidney. There , it stimulates the generation
of cyclic AMP and enhances the permeability of the
tubular epithelium to wa»er.
ADH controlled by two factors: (1) plasma osmolality:
above 285 mosm per liter (osmotic threshold)
concentration of ADH • The regulation effect represented
by a negative feed back mechanism.
(2) A 5% or greater decrease in plasma volume stimulates
ABH release which results in free water retention in
addition to:
Oxytocin : The synthesis of oxytocin as a part of a
p.rohormone containing neurophysin II and it? transport
down the neurohypophyseal tract occur in a fashion analagous
to that of vasopressin. A stimulus for its release
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is suckling. The hormone acts on the myoepithelial
cells of the breast to produce milk ejection.
Diagnostic pituitary stUdies:
~kull films should ’be obtained in patients whaae
signs, and symptoms lead to the suspicion of pituitary
disorder. Lateral films will demonstrate the sagittal
profile of ,the sella turcica and anteroposterior films,
properly taken, will demonstrate the floor of the sella,
but only the posterior, anterior and inferior aspects
on the pituitary can be evaluated by these films. Tomography
provide a more certain assessment of the sella
turcica and are especially helpful for the stUdy of
small microadenoma. The lateral aspect of the pitUitary
can be assessed only by ~giography, and the superior
aspect can be visualized only by pne~encephalography.
~ince patients will often develop some degree of malaise
following pneumoencephalography, angiograms usually are
perforuled first. These radiological studies maJ be
strssfuU and patients with a disordered pituitary-adrenal
axis should be protected with supplementary adrenal steroids
during their r~diographic studies.
Not all patients with enlargement of the sella
turcica have pitUitary tumours fUlly 10 percent of this
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group have the ElIllptysella turcica syndrome. in which
pneumencephalographyreaul ts in filling of the sella
with air. The etiology of this syndromeis unclear.
Should endocrine studies point to a hyper secreting
tumours. The sella nonetheless should be explored as
a moderate number of microadenomashave been removed
from so called eIIlptysellas.
Therapeutic modalities:
Transcranial surgery:
Before the era of antibiotics surgeons were relactan
t to open the frontal sinus to reach the pi tui tary •
the intracranial route w~ via a lateral subfrontal or
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temporal approach. Antibiotics made it possible for
surgeons to remove the frontal bone and if needed to
open the frontal s.iJ’luswithout fear of meningitis.
Work.iJ’lgthrough the frontal S.iJ’lU8pel’Glits less retraction
of frontal lobe and better exposure of the
pituitary. Experienced surgeons can perfol’Gl transfrontal
pituitary surgery fo» hypophysectomyand for tumours
with little morbidity or mortality. This approach
allows the surgeon to visualize the anatomical variationa
that frequently surround the pituitary and to
aDsay the distortions of the surround.iJ’lgneural and
vascufaz- structures that result from tUlliourgrowth.
Transsphenoidal approaches:
The advantages of the transspheno.idal approaches
to the pituitary were recognized. Yet the high incidence
of inftlction in the preantibiotic era worked against
this approach. After opening the frontal sinus dur.iJ’lg
pituitary surgery was proved safe. The trananasal approach
throUgh the sphenoid sinus was again employed •
Although this approach does not allow the surgeon to
visualize intracranial anatomical variations or the
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variable distortions that occur with large tumours.
It is coametically superior since the incision is
hidden in the gingi”al mucos a of the upper lip •
Experience has verified that this approach to the
pituitary is safe and in recent years it has supplanted
the transfrontal intracranial approach in
wost clinics • This procedure demands an operative
microscope and fluoroscopy.
Stereotaxic. techniques:
Because the sella turcica is such a convenient
radiographic target, the pituitai has been treated
by a variety of sterotoxic techniques. Many of these
techniques were developed for the purpose of hypophysectomy
in the treatmant of metastatic cancer,but
in selected cases. the same techniques have been employed
in the treatment of pituitary tumours. In most instances
the cannula employed in ster~otaxic pituitary surgery
is introduced by the transsphenoidal or transethmoidal
route. Radiographic control is essential. but these
procedures can be performed under local anesthesia.
Radioactive gold. radioactive Yttrium. cryosurgery
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ane radiofrequency generators have been employed
with good success to destroy the normal pituitary
and to treat certain pituitary tumours. A major
problem with stereotaxic procedures has been the
high incidence of cerebrospinal fluid rhinorrhea.