Pituitary gland

• Anatomy
• Histology
• Physiology
• Diseases of pituitary gland

Anatomy of pituitary gland

• Pituitary gland lies in the base of the skull in a portion of sphenoid bone called s.t
• It consist of tow lobe anterior lobe (adenohypophysis),and posterior lobe (neurohypophysis)
• The size of the gland which the anterior lobe consist 2/3 varies considerably
• It measures 15X10X6 mml wt 500-900 mg
• It may double in size during pregnancy

Sella turcica of the sphlenoid bone

Location of the Pituitary

Blood supply

• Most richly vascularized of all mammalian tissues,receiving 0.8 ml/min from portal circulation.
• It supply by middle inferior and superior hypophysial arteries from the internal carotid arteries

The Hypothalamic-Hypophyseal Portal System

2 capillary beds directly joined by blood vessels

Histology of the PG 1

Anterior pituitary cells were originally classified as

• Acidophils cells
• Basophils cells
• Chromophope cells

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Histology of PG 2

Now with immunocytochemical and electron microscopic techniques,classified cells by their secretary products

• Somatotrophs cells a. GH secreting cells b. Account about 50% of anterior P.G c. Acidophilic stained

Histology of PG 3

• Lactotrophic a. Prl secreting cells b. acidophilic stained c. 10-15% of anterior PG
• Thyrotrophis a. TSH secreting cells b. basophilic cells c. < 10% of anterior PG

Histology of PG 4

• Corticotrophs a. ACTH secretary cells b. basophilic cells c. 15-20% of anterior PG
• Gonadotrophs a. LH,FSH secretary cells b. basophilic staining c. 10-15% of anterior PG

Anterior pituitary hormone

• GH
• PRL
• TSH
• ACTH
• LH
• FSH

Posterior pituitary hormone

• VASOPRESSIN

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• OXYTOCIN

hypopituitarism

• Hypopituitrism is manifested by diminished or absent secretion of one or more PH
• The development of sign and symptom is often slow and insidious
• Hypo pit is either primary event caused by destruction of APG or 2ndary resulting from deficiency of hypothalamic SF
• Treatment and prognosis depend on the extent of hypofunction,the underlying cause and the location of the lesion

Hypopituitarism

• Is usually gradual and may have single hormone deficiency or multiple hormone
• GH deficiency

a. deficiency in children lead to short stature

b. deficiency in adult lead to vague non specific symptoms,fatigue decrease muscle mass,loss of libido

Gonadotrophin H.D (hypogonadism)

• In women

a. before puberty primary amenorrhea and failure of puberty development

b. after puberty 2ndary amenorrhea and regression of 2ndary sexual characteristic

c. infertility

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hypogonadism

• In men

a. before puberty failure of puberty development

b. after puberty decrease libido or impotence loss of 2ndary sexual characteristic infertility

TSH deficiency lead to 2ndary hypothyroidism

• Clinical feature

cold intolerance

dry skin,loss of hair

mental dullness

constipation

increase in wt

bradycardia,slow reflexes

hoarseness, puffiness of the face

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ACTH deficiency lead to 2ndary adrenocortical insufficiency

• Clinical feature

Weakness

Nausea and vomiting

Anorexia

Wt loss

Postural hypotension

Causes of hypopituitarism

• Infarction

postpartum necrosis (Sheehan syndrome)

vascular disease

head trauma

• Infections

tuberculosis , fungi

pyogenic , syphilis

toxoplasmosis

Hypopituitarism 2

• Granulomas

Sarcoidosis

Histiocytosis

• Autoimmune lymphocytic hypophysitis
• Neoplasm's involving pituitary

Pituitary adenoma

Craniopharyngioma

Metastasis or or primary carcinoma (rare)

Hypopituitarism 3

• Aneurysm of internal carotid artery
• Hemochromatosis
• Idiopathic or genetic

deficient production of pituitary hormone

synthesis of abnormal hormone

• Iatrogenic

stalk section

radiation

hypophysectomy

Hypopituitarism 3

• Primary hypothalamic disorders

tumor (craniopharyngioma)

granulomas (histiocytosis x)

genetic or idiopathic releasing H.D

head trauma

structural anomalies of hypothalamus

Diagnosis of PD by PH stimulation test

Pituitary stimulation test 2

Treatment of hypopituitrism

Pituitary tumors

• Nearly always benign account for 10% of intracranial neoplasm
• Pituitary microaadenoma is intrasellar adenoma less than 1 cm in diameter
• Pituitary macroadenoma are those larger than 1 cm in diameter

Type of pituitary tumors

Clinical presentation of pituitary tumours

• Hormone hypersecretion

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• Space occupying lesion
• Headaches
• Visual loss (field defect)

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• Hormone deficiency states
• Interference with surrounding normal pituitary

Tumours of the anterior pituitary can cause syndromes of hormone excess

• GH

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• ACTH

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• TSH

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• LH/FSH

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• PRL

Acromegaly

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Cushing’s disease

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Secondary thyrotoxicosis

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(Non-functioning pituitary tumour)

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Prolactinoma

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Treatment of P.T

• Surgical

Transfrontal or transsphenoidal

• Radiological

Conventional irradiation,heavy particle I

• Medical

Dopamine agonist (bromocriptin)

Somastatin analog (octreotide)

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