



































 

 

 

Anatomy and physiology of pituitary gland 

 

Dr. Qaiswer Shah Lakanwal1 

Teaching Assistant 

Lecturer at Anatomy and Histology Department in Medical Faculty 

Shaikh Zayed University, Khost, Afghanistan 

qiswer@gmail.com 

 

 

 

 

 

 

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Abstract

The pituitary  gland,  known  as  the  “master  gland,”  is  involved  in  the 

homeostatic regulation of numerous body functions as well as in governing 

reproduction and  childbirth.  Found  at  the  base  of  the  skull,  surrounded  by 

cranial  nerves  and  critical  blood  vessels,  it  is  composed  of  the 

adenohypophysis  and  neurohypophysis.  The  adenohypophysis  is  controlled 

by  the  hypothalamus  via  releasing/inhibiting  hormones  released  into  the 

pituitary  portal  veins  to  secrete  adrenocorticotropic  hormone,  thyroid-

stimulating hormone, growth hormone, follicle-stimulating hormone, luteinizing 

hormone,  and  prolactin.  These  govern  four  major  hormone  systems:

adrenal, thyroid, growth hormone, and reproduction/lactation. These systems 

are regulated  by feedback loops from the effector hormones. The posterior 

pituitary  gland is  directly  stimulated  by  the  hypothalamus  to  produce

vasopressin  for  fluid  homeostasis  and  oxytocin  for  lactation  and  uterine 

contraction.  Dysfunction  or  over  activity  of  any  of  these  hormones  can 

affect  multiple  organ  systems.  It  is  important  to  understand  the  normal 

anatomy  and  physiology  of  the pituitary  gland to  help  diagnose  and  treat 

patients with pituitary disorders

mailto:qiswer@gmail.com


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Keywords
Pituitary  gland,hypothalamus,homeostasis,feedback  loop,adrenal  gland,

thyroid gland, growth hormone,reproductive system,prolactin.

Introduction

Along  with  the  nervous  (central  nervous  system  (CNS))  and circulatory

systems, the endocrine system coordinates and integrates a huge variety of

vital  body  functions.  The blood  circulation  is  a  main  carrier  for  the

hormones’ distribution  to  targettissues.  The neurosecretory cells  of  the 

hypothalamus  produceand  release  the neurohormones that  through  the

anterior  andposterior  lobes  of  the pituitary  gland (PITUITARY  GLAND)

stimulate  the synthesis  and  secretion  of  different  hormones  into  the 

bloodstream,  which  regulate  and maintain  the  control  of  theadrenal  and

thyroid  glands  and  gonads  through  the  cascadeof  complex  neuroendocrine

feedback  and a  number  of  neuronal  peripheral mechanisms.  The  focus  of

this  article  is  the  organization of  the PITUITARY  GLAND, the  major  elements

of  the  neuroendocrine  pathways,  and  the  role  of  the PITUITARY  

GLAND in the control and modulation of a variety of vital body functions.

The Brief History of the pituitary gland

The  first  historical  description  of  the pituitary  gland (hypothesis)  was

provided  by  Galen  (AD  150)  who  proposed  the  potential  role for  the 

found anatomical structure as a draining passage for the phlegm from the 

brain to the  nasopharynx.  In  1742,  Joseph Lieutaud  discovered  the 

pituitary–portal blood

system (hypothalamic–hypophyseal  axis),  and  Saucerotte  was  the first  to 

describe acromegaly in 1772. The gland was for thefirst time fully 

described in 1778



 

 

 

by Soemmering and called‘hypophysis cerebri.’ The anatomical formation of 

the PITUITARY GLAND was described by Rathke in 1838. The posterior 

part of the PITUITARY GLAND wasinvestigated by Oliver and Schafer in 

1895 and by Dale in 

1906, who discovered the vasopressor and oxytocic activitiesof the posterior 

pituitary, showing antidiuretic and galactokinetic properties. The first solid 

description of the clinical symptoms and pathology of the PITUITARY 

GLAND was provided by Minkowski in1887 and Vassale and Sacchi in 

1892, who demonstrated thatsurgically removing the PITUITARY GLAND 

(hypophysectomy) causes irreversible change on the water and mineral 

metabolisms of the body,and it also has been stated that overdevelopment 

and hyperfunction of the PITUITARY GLAND cause acromegaly. The first 

experimentallinks between the reproductive organs and PITUITARY GLAND 

were demonstrated via hypophysectomy leading to dwarfism in 

growinganimals in 1909, by Aschner, and by Cushing in 1910. 

 

 

 

 

Development and Basic Anatomy of the pituitary gland 

 

Development 

Complex development of the PITUITARY GLANDis occurring at the early 

stage of embryogenesis and linked to that of the forebrain. The PITUITARY 

GLAND 

contains three lobes that have dual embryonic origins: anterior lobe 

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(adenohypophysis), intermediate lobe derived from Rathke’s pouch (the 

primitive pharynx), and posterior lobe, whichdevelops from the infundibulum 

(a stalk derived from theregion of the ventral diencephalon). The anterior 

pituitarylobe (adenohypophysis) and posterior pituitary lobe 

(neurohypophysis) both develop from Rathke’s pouch. During 

thedevelopment anterior pituitary loses contact with the oral cavity and the 

posterior pituitary stays connected with the base ofthe hypothalamus. 

Adenohypophys and neurohypophysisbasically are joined together in the 

sella turcica (turkish saddle)at the base of the middle cranial fossa. The 

forming of theanterior pituitary (adenohypophysis) primordium is controlledby 

a complex signal emanating from the ventral diencephalon/infundibulum and 

from Rathke’s pouch, and after that,Rathke’s pouch forms a sac that 

differentiates and forms theadenohypophysis, connecting to the 

hypothalamus via stalk. The 

molecular nature of extrinsic signals and especially 

transcriptionfactors/morphogenes that are involved in the patterning of many 

other organs, lineage specification, and cell type-specific geneexpression in 

pituitary organogenesis has been recently investigated. The ectodermal 

primordium of Rathke’s pouch is foundto be induced by two major signals 

emanating from the diencephalon: BMP4 (bone morphogenetic proteins), 

inducing theformation of the pouch rudiment, and FGF8 (fibroblast 

growthfactor), activating the key regulatory gene and development ofthe 

rudiment into a Rathke’s pouch. Highly regulated geneexpression of the 

controlling processes of cell proliferation 

and appearance of specific transcription factors allow the formation of gland 

cell types. A human PITUITARY GLAND embryogenesis andforming of the 

neuronal posterior pituitary and nonneuronalanterior pituitary tissues are 

usually complete at 12 weeks ofgestation. 

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Basic Anatomy of the PITUITARY GLAND 

 

The PITUITARY GLAND, which is a relatively small anatomical structure 

that is situated deep within the head, at the base of the skull, deep in the 

pit of the sphenoid bone, is surrounded by the optic chiasm, blood vessels, 

and other important brain structures. It consists of the larger part (80% of 

the PITUITARY GLAND size) called anterior pituitary lobe 

(adenohypophysis), intermediate lobe, and posterior pituitary lobe (or 

neurohypophysis), connected to the hypothalamus by the pituitary stalk. The 

adenohypophysis is composed of (a) pars distalis, containing epithelial cells 

surrounded by capillaries and fibers, with the cells being divided into 

acidophils (predominantly located in the lateral part of the lobe), basophils 

(concentrated in the central portion of the pars distalis), chromophils, and 

chromophobes, (b) pars intermedia, and (c) pars tuberalis. Acidophils 

consist of somatotrophs which produce growth hormone (GH), mammotrophs 

which produce prolactin (PRL), basophils consist of gonadotrophs which 

produce follicle-stimulating hormone (FSH), thyrotrophs which produce 

thyrotropin releasing 

hormone (TSH), and corticotrophs which produce adrenocorticotropic 

hormone (ACTH). Cromophils consist of cytoplasm with a large number of 

secretory granules in difference from chromophobes which consist of 

cytoplasm with no secretory 

granules. Pars inter media is located between the pars distalis and pars 

tuberalis and contains small basophilic cells. Pars tuberalis is a part of the 

adenohypophysis around the infundibulum, composed of basophilic cells that 

secrete gonadotrophs (luteinizing hormone (LH) and FSH). The 

adenohypophysis is responsible 

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for the majority of the signaling hormones released into the bloodstream 

through the well-developed hypothalamic–- hypophyseal portal capillary 

system that drains into hypothalamic–hypophyseal portal veins and The 

posterior pituitary lobe (or neurohypophysis, consisting of three distinct 

regions: pars nervosa (posterior lobe, 

which includes Herring bodies and pituicytes), infundibulum (pituitary stalk, 

which connects the hypothalamic and hypophyseal systems), and median 

eminence (ME) (which is included as part of the posterior pituitary). The 

pituitary stalk contains the 

fibers of the neurohypophysis connecting the posterior lobe tothe supraoptic 

nucleus (SON) and paraventricular nucleus(PVN) of the hypothalamus and 

the portal venous system,transmitting hypothalamic peptides that control 

anterior lobe 

secretion. 

The pathology of the PITUITARY GLAND leads to the development of 

symptoms dependent on its change of secretion or symptomsdependent on 

the new anatomical intracranial relations thatarise (lesions, tumors, etc.). It 

has been found that lack ofbalanced PITUITARY GLAND hormonal 

secretion could lead to acromegalicgigantism (first time described by Pierre 

Marie in 1886), dwarfism, Frohlich’s disease (dystrophia adiposa genitalis), 

acutepituitary insufficiency (causes fevers and toxemias), and polyglandular 

syndrome (autoimmune disease leading to inflammation, lymphocytic 

infiltration, and partial or completegland destruction). The typical anatomical 

pathology of the PITUITARY GLAND 

is a tumor (Cushing’s disease) indicative of increased intracranial pressure 

causing headache, vomiting, vision impairment,nausea, and partial blindness, 

with main symptoms such asweak immune system, osteoporosis, extreme 

hair growth on 

face, fatigue, and cognitive dysfunctions  

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Neurovascular link between hypothalamus and pituitary gland 

 

The pituitary stalk comprises mainly neural and vascular components, 

though an incomplete layer of epithelial cells, the pars tuberalis, whose 

function is uncertain, covers its ventral aspect .The bulk of the stalk is 

made up of neural tissue in 

which lie the various coiled capillary vessels on whichend the nerve fibres 

that are derived from cells in the hypophysiotrophic area. The 

neurohormones coming down these nerve fibres are transferred from the 

endings of the fibres into the blood passing through the coiled capillaries, 

and thus into the portal vessels. These portal vessels, as was first pointed 

out by Xuereb et al. (1954b), can be classified as long and short. The 

origin of the vessels which supply them makes a distinction most important. 

The afferent arterioles to the coiled capillaries from which 

the long portal vessels are derived spring from the arterial ring supplied by 

the superior hypophysial arteries (arising from the internal carotid arteries 

above the level of the diaphragma sellae), while those which supply the 

coiled capillaries that form the short portal vessels are derived from the 

inferior hypophysial arteries, which leave the internal carotid arteries within 

the cavernous sinus. The long portal vessels run down the pituitary stalk to 

supply the larger part of the pars distalis, while the short portal vessels 

supply a restricted part of the lobe adjacent to that part of the lower 

infundibular stem which is buried in the pars distalis. Xuereb et al. (1954a, 

b) describe this system of vessels, and Daniel and Prichard (1975) also 

describe the system in other species. A portal system of vessels is found 

in all vertebrates, and a valuable recent study is of that in the horse 

(Vitums, 1975). 

When the pituitary stalk is cut surgically, to try to produce regression of 

various forms of carcinoma 

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Hormones of the Adenohypophysis 

 

The different cells of the adenohypophysis synthesize and release into the 

bloodstream vital endocrine hormones such as ACTH (secreted by 

corticotrophs), TSH (secreted by thyrotrophs), FSH (secreted by 

gonadotrophs), LH (secreted by gonadotrophs) in females also known in 

males as interstitial cell-stimulating 

hormone, growth hormone (GH, secreted by somatotrophs), GHRH (secreted 

by somatotrophs), PRL (secreted by lactotrophs), and melanocyte-stimulating 

hormone (a-MSH, secreted by melanotrophs). All those hormones can be 

classified into three major groups: glycoproteins (TSH, LH, and FSH 

composed of a common a-subunit and a hormone-specific b-subunit), 

growth hormones (GH and GHRH), and proopiomelanocortins (a-MSH, 

regulating the production and distribution of melanin by melanocytes) 

Hormones of the Neurohypophysis 

 

The large (magnocellular) neurons located in the SON and PVN of the hypothalamus 

synthesize and transport along the axons to terminals situated within the posterior lobe of 

the PITUITARY GLAND (neurohypophysis) two vital hormones: oxytocin and VP (or 

antidiuretic hormone (ADH)), which are secreted by calcium-dependent exocytosis. The 

posterior pituitary hormones are transported in association with specific proteins, the 

neurophysins, via the ‘unmyelinated’ nerve fibers that extend through the infundibulum 

along with small cellscalled pituicytes to end in nerve terminals that lie withinthe 

posteriorlobe; prior to secretion, they are stored in secretory granules in the Herring bodies. 

The oxytocin stimulates contraction of the uterus during labor, prevents posttraumatic 

hemorrhage, and is involved in lactation and milk ejection from the nipples, sexual arousal, 

suppressing appetite, etc. Oxytocin is also called the ‘love and bonding hormone’ that plays 

an important role in social recognition (especially in trust, empathy, rejection, and 

suspicions in the group), increasing positive attitudes, the formation and realization of 

maternal instinct, orgasm, depression and anxiety, wound healing, and soothing 

inflammation. Oxytocin receptors are expressed by neurons not only in the neurohypophysis 

but also in the septum, nucleus accumbens, brain stem, amygdala, and other parts of the 

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brainand body. The chemical structure of VP (ADH) is very\ similar to 

oxytocin, and this is why oxytocin has milddiuretic properties, and high 

levels of ADH can cause uterine contractions. The main functions of the 

ADH are waterretention and maintaining normal body fluid volume 

viaspecific renal (V2) and vascular (V1) receptors, regulation ofbody 

temperature, initiation of aggressive behavior, and 

male pair-bonding behavior. ADH produces vasodilationin the renal, 

pulmonary, cerebral, and mesenteric vascularbeds by stimulating endothelial 

nitric oxide (NO) releaseand increases the systemic blood pressure. ADH is 

alsoinvolved in the modulation of the corticosteroid releasefrom the adrenal 

gland in response to stress during pregnancy and lactation and also may 

cause an analgetic (nociceptive) effect during sex and stress. ADH 

demonstrates 

anti-inflammatory properties via inhibition of the inflammatory cytokine 

interleukin-1 released in response totrauma or infection. ADH deficiency, as 

a result of the 

hypothalamic–neurohy pophyseal lesions or in sensitivity ofthe kidney to 

ADH in nephrogenic diabetes insipidus, leadsto dehydration, diarrhea, 

hyperosmolality, and eventualdeath. ADH overproduction promotes excessive 

water retention and hyponatremia, which may cause convulsions andcoma. 

ADH could be effective in reversing hypotensionproduced by septic shock 

and could be a useful therapy 

for hypovolemic cardiac arrest. 

Conclusion 

Recent advances using a wide range of methodologies provide more 

detailed knowledge and generate new valuable insights about the cellular, 

molecular, and genetic mechanisms involved in the anatomy, organization, 

development, and 

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function of the human PITUITARY GLAND. The recognition of the 

fascinating 

role of the PITUITARY GLAND and its sophisticated hormonal system, 

which is 

a retrograde regulator of hypothalamic and peripheral endocrine functions, 

raises important questions regarding the extraordinary complexity and vital 

role of the PITUITARY GLAND in neuroendocrine regulation of a huge 

variety of human physiological functions on molecular, organic, and systemic 

levels that 

remain virtually not fully explored.  

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	Keywords

