Pituitary Gland

Dr: Azza ZakiDr: Azza Zaki


Pituitary Gland (Hypophysis Cerebri)Pituitary Gland (Hypophysis Cerebri)It is the master endocrine gland, because it controls the other endocrine glands & body growth.

It is attached to the under-surface of the brain (hypothalamus)hypothalamus) by the infundibulum (stalk).


PituitaryPituitary GlandGlandLocation:Location:

Small, slightly Small, slightly oval oval gland lies in the gland lies in the hypophyseal fossahypophyseal fossa (sella turcica)(sella turcica) of the of the sphenoid bone.sphenoid bone.

It is covered by an covered by an extension of the dura extension of the dura matter, matter, diaphragma diaphragma sellaesellae..


RelationsRelationsSuperiorlySuperiorly:: The The diaphragma diaphragma sellaesellae, which separates , which separates the gland from the the gland from the opticoptic chiasma.chiasma. LaterallyLaterally:: cavernouscavernous sinus &its sinus &its contents. contents. InferiorlyInferiorly:: body of the body of the sphenoid and sphenoid and sphenoidal sinussphenoidal sinus separating the gland separating the gland from nasopharynx.from nasopharynx.


RelationsRelations AnteriorlyAnteriorly::

Tuberculum sellae Tuberculum sellae

Sphenoidal sinus Sphenoidal sinus

The nasal cavity.The nasal cavity.

PosteriorlyPosteriorly::

Dorsum sellaeDorsum sellae

Basilar artery. Basilar artery.

The pons The pons


Development Of The Pituitary GlandDevelopment Of The Pituitary Gland

The pituitary gland is The pituitary gland is ectodermal in origin,ectodermal in origin, develops from 2 sources: develops from 2 sources: Anterior lobeAnterior lobe or adenohypophysis: it arises from a small or adenohypophysis: it arises from a small ectodermal ectodermal

diverticulum diverticulum ((Rathke’s pouch)Rathke’s pouch) grows from the roof of thegrows from the roof of the stomodeum stomodeum (mouth).(mouth).

Posterior lobePosterior lobe or neurohypophysis: a small or neurohypophysis: a small ectodermal ectodermal diverticulum diverticulum (the (the infundibuluminfundibulum) which grows from the floor of the ) which grows from the floor of the diencephalon.diencephalon.


Lobes Of The Pituitary GlandLobes Of The Pituitary Gland


Hypophysis cerebri actually consists of 2 glands Hypophysis cerebri actually consists of 2 glands that are united anatomically but functions that are united anatomically but functions

differently.differently.

Pars DistalisPars Distalis(anterior lobe)(anterior lobe)

Pars Pars IntermediaIntermedia

Pars Pars TuberalisTuberalis

NeurohypophysisNeurohypophysis AdenohypophysisAdenohypophysis

InfundibulumInfundibulum Pars NervosaPars Nervosa


Lobes Of The Pituitary GlandLobes Of The Pituitary GlandThe pituitary gland is divided into:The pituitary gland is divided into:An anterior lobe, or adenohypophysis:An anterior lobe, or adenohypophysis: is subdivided into: is subdivided into: the pars anterior (pars distalis),the pars anterior (pars distalis), the pars intermedia, which may be the pars intermedia, which may be separated by a cleft (remnant of an separated by a cleft (remnant of an embryonic pouch)embryonic pouch)The pars tuberalisThe pars tuberalisA posterior lobe or neurohypophysis:A posterior lobe or neurohypophysis: pars nervosa & stalkpars nervosa & stalk


Blood SupplyBlood SupplyArterial supply:Arterial supply:

from from superiorsuperior &&inferior hypophysealinferior hypophyseal branches of the branches of the internal internal carotidcarotid artery. artery.

Venous drainage:Venous drainage: cavernous and cavernous and intercavernous sinuses.intercavernous sinuses.

Receives venous bloodReceives venous blood from from hypothalamus hypothalamus viavia hypothalamo-hypophyseal hypothalamo-hypophyseal portal venous system portal venous system which which transmits releasing factors transmits releasing factors to the to the anterior lobeanterior lobe of the of the pituitary gland to control the pituitary gland to control the release of its hormones.release of its hormones.


Control Of The Pituitary GlandControl Of The Pituitary Gland

Nervous

Hypothalamo-hypophyseal tract to posterior lobe

Vascular

Hypothalamo hypophyseal portal system to anterior lobe


Connections Of The Hypothalamus With Connections Of The Hypothalamus With The Hypophysis CerebriThe Hypophysis Cerebri

The hypothalamus is The hypothalamus is connected to the pituitary connected to the pituitary gland by:gland by:Hypothalamohypophyseal Hypothalamohypophyseal tract:tract: nerve fibers that travel nerve fibers that travel from the supraoptic & from the supraoptic & paraventricular nuclei to the paraventricular nuclei to the posterior lobeposterior lobe of the of the hypophysis.hypophysis.Hypophyseal portal system:Hypophyseal portal system: long & short portal blood long & short portal blood vessels that connect sinusoids vessels that connect sinusoids in the median eminence& in the median eminence& infundibulum with capillary infundibulum with capillary plexuses in the plexuses in the anterior lobeanterior lobe of the hypophysisof the hypophysis


Hypothalamohypophyseal TractHypothalamohypophyseal TractThe hormones The hormones vasopressin vasopressin (antidiuretic ADH)& oxytocin(antidiuretic ADH)& oxytocin are are synthesized in the synthesized in the supraopticsupraoptic & & paraventricularparaventricular nuclei.nuclei.The hormones are passed along The hormones are passed along the axons of the the axons of the hypothalamophypophyseal tracthypothalamophypophyseal tract & are released at the axon & are released at the axon terminals, into the blood stream terminals, into the blood stream in capillaries of the in capillaries of the posterior posterior pituitary.pituitary.Oxytocin stimulates:Oxytocin stimulates: the contraction of the uterusthe contraction of the uterus & myoepithelial cells of the ducts & myoepithelial cells of the ducts of the breastof the breast


Hormones of the Posterior PituitaryHormones of the Posterior Pituitary


hypothalamo-hypophyseal portal hypothalamo-hypophyseal portal venous systemvenous system

The portal The portal system carry system carry releasing releasing hormones and hormones and release –release –inhibiting inhibiting hormoneshormones from from hypothalamus hypothalamus to anterior to anterior lobe of lobe of pituitary.pituitary.


hypothalamo-hypophyseal portal systemhypothalamo-hypophyseal portal system The The Superior hypophyseal Superior hypophyseal

arteriesarteries arise from the arise from the internal carotid arteries,internal carotid arteries, supply the median eminence, supply the median eminence, the infundibulum and adjacent the infundibulum and adjacent parts of the anterior lobe.parts of the anterior lobe.

form a form a primary capillary primary capillary plexusplexus that irrigate that irrigate infundibulum and the median infundibulum and the median eminence.eminence.

Rejoins to form hypophyseal Rejoins to form hypophyseal veinsveins

that develops a that develops a secondary secondary capillary plexuscapillary plexus ( (sinusoids) sinusoids) that pass between the that pass between the secretory cells of the secretory cells of the anterior lobe.anterior lobe.


Hypothalamo- hypophyseal portal systemHypothalamo- hypophyseal portal system



Hormones of the Anterior PituitaryHormones of the Anterior Pituitary

Slide 9.17Slide 9.17


The Hormones Of The Anterior PituitaryThe Hormones Of The Anterior Pituitary

ACTH:ACTH: adrenocorticotropic hormone: adrenocorticotropic hormone: stimulate adrenal stimulate adrenal cortexcortex FSH:FSH: follicle stimulating hormone: follicle stimulating hormone: stimulates growth of stimulates growth of follicles in the ovary & spermatogenesis in the testis.follicles in the ovary & spermatogenesis in the testis.LH:LH: luteinizing hormone: luteinizing hormone: stimulates secretion of estrogen stimulates secretion of estrogen & progesterone & ovulation (in female)& progesterone & ovulation (in female)Interstitial cell stimulating hormone (ICSH): stimulate Interstitial cell stimulating hormone (ICSH): stimulate release of testosterone (in male).release of testosterone (in male).TSH:TSH: thyrotropic hormone or thyroid stimulating hormone. thyrotropic hormone or thyroid stimulating hormone.GH:GH: growth hormone: growth hormone: stimulate the body growthstimulate the body growthMSH:MSH: melanocyte- stimulating hormone melanocyte- stimulating hormoneProlactin (LTH):Prolactin (LTH): luteotropic hormone (lactogenic hormone: luteotropic hormone (lactogenic hormone: stimulates milk secretion by mammary gland during lactationstimulates milk secretion by mammary gland during lactation


Clinical NotesClinical Notes


Pituitary Enlargement (Tumor) And Pituitary Enlargement (Tumor) And The Optic ChiasmThe Optic Chiasm

Since the pituitary is located in the bony sella turcica, Since the pituitary is located in the bony sella turcica, enlargement causes it to enlargement causes it to expand superiorly.expand superiorly.A pituitary tumor classically pushes the diaphragma sellaeA pituitary tumor classically pushes the diaphragma sellae

upward and causes upward and causes pressure on the optic chiasmapressure on the optic chiasma.. This This results in interference with the function of the nerve fibersresults in interference with the function of the nerve fibers

crossing in the chiasma (from the inner quadrants of thecrossing in the chiasma (from the inner quadrants of the

retina), and the patient presents with retina), and the patient presents with bitemporal bitemporal hemianopiahemianopia is a loss of the lateral halves of the fields of is a loss of the lateral halves of the fields of vision of both eyes (loss of function of the medial half of vision of both eyes (loss of function of the medial half of both retinas).both retinas).

Further expansion of the pituitary tumor causes Further expansion of the pituitary tumor causes erosion of erosion of the body of the sphenoid bone the body of the sphenoid bone (x-ray: (x-ray: ballooningballooning

of the sella turcica).of the sella turcica).


Sella turcica


Surgical ApproachSurgical Approach

Trans-cranial (subfrontal approach):Trans-cranial (subfrontal approach): the gland can be approached through the the gland can be approached through the anterior cranial fossa by elevating the anterior cranial fossa by elevating the frontal lobe of the brain .frontal lobe of the brain .

Trans-sphenoidal approach: Trans-sphenoidal approach: entering the pituitary fossa through the entering the pituitary fossa through the sphenoidal air sinus .sphenoidal air sinus .


DwarfismDwarfism

A deficiency in the growth hormone secreted by the somatotrope cells of the pars anterior during childhood leads to pituitary dwarfism. Growth does not stop entirely, and the different parts of the body are in relatively normal proportions.The person is of normal intelligence, but the facial skin is often wrinkled and sexual maturation is delayed.


Gigantism and AcromegalyGigantism and AcromegalyExcessive production of the growth Excessive production of the growth hormonehormone by the somatotrope cells of by the somatotrope cells of the pars anterior or by tumors of these the pars anterior or by tumors of these cells can produce abnormal growth of cells can produce abnormal growth of the skeletonthe skeleton. Gigantism. Gigantism occurs occurs in the in the youngyoung before the epiphyses in long before the epiphyses in long bones fuse with the diaphysis.bones fuse with the diaphysis. AcromegalyAcromegaly is a form of abnormal is a form of abnormal skeletal and soft tissue skeletal and soft tissue growthgrowth that that occurs occurs after adolescenceafter adolescence,, following the following the fusion of the epiphyses in long bones fusion of the epiphyses in long bones with the diaphysis. In this disease, the with the diaphysis. In this disease, the individual cannot grow taller, but individual cannot grow taller, but overgrowth occurs in the bones and overgrowth occurs in the bones and soft tissues of the forehead, nose, soft tissues of the forehead, nose, lower jaw, hands, and feet. lower jaw, hands, and feet.


Diabetes InsipidusDiabetes InsipidusThis syndrome results from a lesion of This syndrome results from a lesion of the the supraoptic and paraventricular nucleisupraoptic and paraventricular nuclei of the of the hypothalamus and a failure of these cells to hypothalamus and a failure of these cells to synthesize the antidiuretic hormone, or from synthesize the antidiuretic hormone, or from destruction of the hypothalamohypophysial tract.destruction of the hypothalamohypophysial tract.

There are many causes of this syndrome, including There are many causes of this syndrome, including cerebral tumors, cerebral abscesses, surgical or cerebral tumors, cerebral abscesses, surgical or radiation damage, and head injuries.radiation damage, and head injuries.Characteristically, the patient passes large volumes Characteristically, the patient passes large volumes of urine (polyuria) of low specific gravity. As a of urine (polyuria) of low specific gravity. As a result, the patient is extremely thirsty result, the patient is extremely thirsty


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Pituitary Gland