DR NILESH KATE

MBBS,MDASSOCIATE PROF

DEPT. OF PHYSIOLOGY

PITUITARY GLAND

OBJECTIVES. Introduction and functional anatomy. Anterior pituitary hormones

Growth hormones Applied aspects.

Monday, May 1, 2023

INTRODUCTION AND FUNCTIONAL ANATOMY.

Hypothalamo-pituitary unit– important component of endocrine system

Controls – Growth, Lactation, Fluid balance, thyroid, adrenals & gonads.

Monday, May 1, 2023

GROSS ANATOMY Pituitary Gland –

hypophysis cerebri Wt – 0.5 gm Location –

hypophyseal fossa Suspended by pituitary

stalk which connects it to hypothalamus.

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DEVELOPMENT. Anterior pituitary –

Ectodermal origin. From Rathke’s pouch Upward out pouching from

roof of primitive oral cavity.

Posterior pituitary. Lowered out pouching

From Neuroectodermal tissues of central hypothalamus.

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PARTS OF PITUITARY GLAND. Adenohypophysis Neurohypophysis. Pituitary stalk.

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ADENOHYPOPHYSIS Forms 80% 3 parts Pars Distalis – main

bulk, highly vascular Pars Intermedia –

middle, avascular zone Pars Tuberalis – most

vascular, contains secretory cells.

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NEUROHYPOPHYSIS. Post lobe – Neural structure. 3 parts

Pars Posterior – pars nervosa , forms main bulk.

Infundibular Stem – arising from median eminance

Median Eminance – small portion from base of hypothalamus..

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PITUITARY STALK. Median eminence &

Infundibulum forms neural stalk.

Surrounded by Pars Tuberalis of Adenohypophysis.

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INTERMEDIATE LOBE Rudimentary & does not secrete

Melanocyte stimulating hormones(MSH).

Humans contains few Melanocyte containing melanin granules.

ACTH has weak MSH like activity, so in Addison's disease Hyper secretion of ACTH, there is hyper pigmentation of skin.

Monday, May 1, 2023

HISTOLOGICAL STRUCTURE Adenohypophysis

Chromophobes - Agranular Chromophils – Granular

Acidophils (35%) Somatotrophs Mammotrophs.

Basophils (15%) Corticotrophs, Thymotrophs,

Gonadotrophs.

Folliculostellate cells Capillary network.

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HISTOLOGICAL STRUCTURE Neurohypophysis.

Unmyelinated nerve fibers – axons in supraoptic & paraventricular nuclei of hypothalamus.

Pituicytes – Special types of supporting cells.

Glial cells – like Astrocytes & Oligodendrocytes.

Monday, May 1, 2023

BLOOD SUPPLY OF PITUITARY GLAND

ARTERIAL SUPPLY Internal carotid artery

(sup & inf hypophyseal branches)

Anterior cerebral artery. Posterior cerebral

artery.

VENOUS DRAINAGE Cavernous sinus Jugular veins.

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HYPOTHALAMO-HYPOPHYSEAL PORTAL SYSTEM.

From superior hypophyseal artery, form capillary network.

Drained by long portal veins in Infundibulum.

Break into capillaries as sinusoids of pars anterior as portal system

Provide link between ant & post pituitary.

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HYPOTHALAMIC PITUITARY RELASHIONSHIP

Hypothalamo-hypophyseal tract.

Tubero-infundibular tract and hypothalamo-hypophyseal portal system.

Monday, May 1, 2023

HYPOTHALAMO-HYPOPHYSEAL TRACT.

Axons of large Neuro secretory cells of supraoptic & paraventricular nuclei of hypothalamus.

At axon terminal form Herring bodies.

Secrete peptide hormones & stored in Neuro secretory granules in nerve terminals.

Released in inferior hypophyseal artery.

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TUBERO-INFUNDIBULAR TRACT AND HYPOTHALAMO-HYPOPHYSEAL

PORTAL SYSTEM.

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ANTERIOR PITUITARY HORMONES

ANTERIOR PITUITARY - master endocrine organ

Adenohypophysis hormones Growth hormone family. Glycoprotein hormone

family. Pro-opiomelanocortin

peptides family.

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GROWTH HORMONE FAMILY. Growth hormone Prolactin. Human chorionic

Somatomammotropin.

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GLYCOPROTEIN HORMONE FAMILY.

Thyroid stimulating hormone

Luteinizing hormones

Follicle stimulating hormones.

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PRO-OPIOMELANOCORTIN PEPTIDES FAMILY.

Derived from single precursor – Pro-

opiomelanocortin

Adrenocorticotropic hormone

Melanocyte stimulating hormone

β- lipotropin

β-endorphin

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OBJECTIVES WE HAVE SEEN Pituitary gland – macroscopic & Microscopic

structure. Relationship with Hypothalamus. Releasing & Inhibiting Hormones. Anterior pituitary gland Cells, secretions and different hormones.

Monday, May 1, 2023

Thank you.

Monday, May 1, 2023