Anterior pituitary

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Anterior pituitary

The anterior pituitary (also called the adenohypophysis, from Greek adeno, "gland"; hypo, "under"; physis, "growth"; hence, glandular undergrowth) comprises the anterior lobe of the pituitary gland

Pituitary gland

The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g . It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a Dura mater fold ....
and is part of the endocrine system

Endocrine system

The endocrine system is a system of small organs that involve the release of extracellular signaling molecules known as hormones. The endocrine system is instrumental in regulating metabolism, human development , and tissue and also plays a part in determining Mood ....
. Unlike the posterior lobe

Posterior pituitary

The posterior pituitary comprises the posterior lobe of the pituitary gland and is part of the endocrine system....
, the anterior lobe is genuinely glandular, hence the root adeno in its name.

Under the influence of the hypothalamus

Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
, the anterior pituitary produces and secretes several peptide hormone

Peptide hormone

Peptide hormones are a class of peptide that are secreted into the blood stream and have endocrine functions in living animals. Peptide hormones are increasingly being identified in plants with important roles in cell-to-cell communication and plant defence....
s that regulate many physiological processes including stress

Stress (medicine)

Stress is a biological term which refers to the consequences of the failure of a human or animal body to respond appropriately to emotional or body threats to the organism, whether actual or imagined....
, growth

Growth

Growth refers to an increase in some quantity over time. The quantity can be physical or abstract . It can also refer to the mode of growth, i.e....
, and reproduction.

term "pars distalis" is sometimes used as a synonym for the anterior pituitary, but this is not quite correct.

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Encyclopedia

Pituitary gland

Endocrine system

Posterior pituitary

Hypothalamus

Peptide hormone

Stress (medicine)

Growth

Growth refers to an increase in some quantity over time. The quantity can be physical or abstract . It can also refer to the mode of growth, i.e....
, and reproduction.

Regions

The term "pars distalis" is sometimes used as a synonym for the anterior pituitary, but this is not quite correct. The anterior pituitary is usually divided into three regions:

pars distalis ("distal part") - the majority of the anterior pituitary
pars tuberalis
Pars tuberalis

The pars tuberalis is part of the Anterior pituitary, and wraps the pituitary stalk in a highly vascularized sheath....
("tubular part") - a sheath extending up from the pars distalis and wrapping around the pituitary stalk
Pituitary stalk

The pituitary stalk is the connection between the hypothalamus and the posterior pituitary.It carries axons from the magnocellular neurosecretory cells of the hypothalamus down to the posterior pituitary where they release their hormones into the blood....
pars intermedia
Pars intermedia

Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary. It contains three types of cells - Anterior pituitary basophils, chromophobes, and colloid-filled cysts....
("intermediate part") - sits between the bulk of the anterior pituitary and the posterior pituitary and is often very small in humans

The function of the tuberalis is not well characterized, and most of the rest of this article refers primarily to the distalis.

Embryology

Unlike the posterior pituitary

Posterior pituitary

The posterior pituitary comprises the posterior lobe of the pituitary gland and is part of the endocrine system....
(pars nervosa), which originates from neural ectoderm

Ectoderm

The ectoderm is the start of a tissue that covers the body surfaces. It emerges first and forms from the outermost of the germ layers.Generally speaking, the ectoderm differentiates to form the nervous system, Epidermis , and the outer part of integumentary system....
, the anterior pituitary arises from an invagination

Invagination

Invagination means to fold inward or to sheath. In biology, this can refer to a number of processes.*Invagination is the morphogenetic processes by which an embryo takes form, and is the initial step of gastrulation, the massive reorganization of the embryo from a simple spherical ball of Cell , the blastula, into a multi-layered organism,...
of the oral ectoderm

Ectoderm

Rathke's pouch

In embryogenesis, Rathke's pouch is a depression in the roof of the developing mouth in front of the buccopharyngeal membrane. It gives rise to the anterior pituitary, a part of the endocrine system....
.

This differentiation is exhibited by the fact that while the posterior pituitary

Posterior pituitary

The posterior pituitary comprises the posterior lobe of the pituitary gland and is part of the endocrine system....
merely secretes hormones produced in the hypothalamus

Hypothalamus

Oxytocin

Oxytocin is a mammalian hormone that also acts as a neurotransmitter in the brain.It is best known for its roles in female reproduction: it is released in large amounts after distension of the cervix and vagina during labor, and after stimulation of the nipples, facilitating childbirth and breastfeeding, respectively....
), the anterior pituitary actually produces its hormones, while being under control of the hypothalamus

Hypothalamus

Major hormones secreted

Hormone	Other names	Symbol(s)	Secretory cells (staining type)	Target	Effect
Adrenocorticotropic hormone Adrenocorticotropic hormone Adrenocorticotropic hormone is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress ....	Corticotropin	ACTH	Corticotrophs (basophil Anterior pituitary basophil An anterior pituitary basophil is a type of cell in the anterior pituitary which manufactures hormones.It is called a basophilic because it readily takes up Base , and typically stains a relatively deep blue or purple.... )	Adrenal gland Adrenal gland In mammals, the adrenal glands are the star-shaped endocrine glands that sit on top of the kidneys; their name indicates that position . They are chiefly responsible for regulating the stress response through the biosynthesis of corticosteroids and catecholamines, including cortisol and adrenaline, respectively....	Secretion of glucocorticoid Glucocorticoid Glucocorticoids are a class of steroid hormones which bind to the glucocorticoid receptor , which is present in almost every animal cell.GCs are part of the feedback mechanism in the immune system which turns immune activity down.... s
Beta-endorphin Beta-endorphin Beta-endorphin is an endogenous opioid peptide neurotransmitter found in the neurons of both the central nervous system and peripheral nervous system....			Corticotrophs (basophil Anterior pituitary basophil An anterior pituitary basophil is a type of cell in the anterior pituitary which manufactures hormones.It is called a basophilic because it readily takes up Base , and typically stains a relatively deep blue or purple.... )	Opioid receptor	Inhibit perception of pain
Growth hormone Growth hormone Growth hormone is a peptide hormone. It stimulates human development and cell reproduction in humans and other animals. It is a 191-amino acid, single chain polypeptide hormone which is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland....	Somatotropin	GH, STH	Somatotrophs (acidophil)	Liver Liver The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion.... , adipose tissue Adipose tissue In histology, adipose tissue or fat is loose connective tissue composed of adipocytes. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of fat, although it also cushions and Thermal insulation the body....	Promotes growth; lipid Lipid Lipids are broadly defined as any fat-soluble , naturally-occurring molecule, such as fats, oils, waxes, cholesterol, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others.... & carbohydrate Carbohydrate Carbohydrates or saccharides are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy and structural components .... metabolism Metabolism Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
Thyroid-stimulating hormone Thyroid-stimulating hormone Thyroid-stimulating hormone is a peptide hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland....	Thyrotropin	TSH	Thyrotrophs (basophil)	Thyroid gland	Secretion of thyroid hormone Thyroid hormone The thyroid hormones, thyroxine and triiodothyronine , are tyrosine-based hormones produced by the thyroid gland. An important component in the synthesis of thyroid hormones is iodine.... s
Follicle-stimulating hormone Follicle-stimulating hormone Follicle-stimulating hormone is a hormone synthesized and secreted by gonadotropes in the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the human body....	-	FSH	Gonadotrophs (basophil)	Gonads	Growth of reproductive system Reproductive system The reproductive system is a system of Organ within an organism which work together for the purpose of reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system....
Luteinizing hormone Luteinizing hormone Luteinizing hormone is a hormone produced by the anterior pituitary gland.* In the female, an acute rise of LH ? the LH surge ? triggers ovulation....	Lutropin	LH, ICSH	Gonadotrophs (basophil)	Gonads	Sex hormone production
Prolactin Prolactin Prolactin or Luteotropic hormone is a peptide hormone primarily associated with lactation. In breastfeeding, the act of an infant suckling the nipple stimulates the production of prolactin, which fills the breast with milk via a process called lactogenesis, in preparation for the next feed....	Lactogenic hormone	PRL	Lactotroph Lactotroph Lactotrophs are cell in the anterior pituitary which produce prolactin in response to signals including dopamine and estrogen. Dopamine has an inhibitory effect on PRL secretion.... s, also known as Mammotrophs (acidophil)	Ovaries Ovary The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are homology to testicle in males, in that they are both gonads and endocrine glands.... , mammary gland Mammary gland Mammary glands are the organ s that, in mammals, produce milk for the sustenance of the young. These exocrine glands are enlarged and modified sweat glands and give mammals their name.... s	Secretion of estrogen Estrogen Estrogens are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone.... s/progesterone Progesterone Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen.... ; milk Milk Milk is an opaque white liquid produced by the mammary glands of female mammals . It provides the primary source of nutrition for newborn mammals before they are able to digestion other types of food.... production

One mnemonic used to remember the hormones produced by the anterior pituitary is: FLAT PEG (FSH, LH, ACTH, TSH, Prolactin, Endorphins and GH).

Hypothalamic releasing and release-inhibiting factors

Hormone secretion from the anterior pituitary gland is regulated by hormones secreted by the hypothalamus

Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
. Neuroendocrine neurons in the hypothalamus project axon

Axon

An axon or nerve fiber is a long, slender projectionof a nerve cell, or neuron, that conducts action potentialaway from the neuron's cell body or soma....
s to the median eminence

Median eminence

The median eminence is part of the inferior boundary for the hypothalamus part of the human brain. A small swelling on the tuber cinereum posterior to the infundibulum - atop the pituitary stalk - the median eminence lies in the area roughly bounded on its posterolateral region by the cerebral peduncles, and on its anterolateral region...
, at the base of the brain. At this site, these neurons can release substances into small blood vessels that travel directly to the anterior pituitary gland (the hypothalamo-hypophysial portal vessels).

Name	Other Names	Abbreviations	Location	- \| Corticotropin-releasing hormone Corticotropin-releasing hormone Corticotropin-releasing hormone , originally named corticotropin-releasing factor , and also called corticoliberin, is a polypeptide hormone and neurotransmitter involved in the stress ....	Corticotropin-releasing factor, Corticoliberin	CRH, CRF	parvocellular Parvocellular Parvocellular can refer to:* Parvocellular part* part of the Paraventricular nucleus of hypothalamus... neuroendocrine neurons in the paraventricular nucleus Paraventricular nucleus The paraventricular nucleus is a neuronal nucleus in the hypothalamus. It contains multiple subpopulations of neurons that are activated by a variety of stressful and/or physiological changes....	with vasopressin Vasopressin Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a hormone found in most mammals, including humans.... , stimulates secretion of ACTH Adrenocorticotropic hormone Adrenocorticotropic hormone is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress .... \|- \| Dopamine Dopamine Dopamine is a neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In the human brain, this phenethylamine functions as a neurotransmitter, activating the five types of dopamine receptors ? D1, D2, D3, D4 and D5, and their variants....	Prolactin-inhibiting hormone	DA, PIH	neuroendocrine neurons of the arcuate nucleus Arcuate nucleus The arcuate nucleus is an aggregation of neurons in the mediobasal hypothalamus, adjacent to the third ventricle and the median eminence. The arcuate nucleus includes several important populations of neurons, including: Neuroendocrine neurons, Centrally-projecting neurons and Others....	inhibits secretion of prolactin Prolactin Prolactin or Luteotropic hormone is a peptide hormone primarily associated with lactation. In breastfeeding, the act of an infant suckling the nipple stimulates the production of prolactin, which fills the breast with milk via a process called lactogenesis, in preparation for the next feed.... \|- \| Gonadotropin-releasing hormone Gonadotropin-releasing hormone Gonadotropin-releasing hormone , also known as Luteinizing-hormone releasing hormone , is a tropic hormone peptide hormone responsible for the release of follicle-stimulating hormone and luteinizing hormone from the anterior pituitary....	Luteinising-hormone releasing hormone	GnRH, LHRH	neuroendocrine neurons in the medial preoptic and arcuate nuclei Arcuate nucleus The arcuate nucleus is an aggregation of neurons in the mediobasal hypothalamus, adjacent to the third ventricle and the median eminence. The arcuate nucleus includes several important populations of neurons, including: Neuroendocrine neurons, Centrally-projecting neurons and Others....	stimulates secretion of LH Luteinizing hormone Luteinizing hormone is a hormone produced by the anterior pituitary gland.* In the female, an acute rise of LH ? the LH surge ? triggers ovulation.... and FSH Follicle-stimulating hormone Follicle-stimulating hormone is a hormone synthesized and secreted by gonadotropes in the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the human body.... \|- \| Growth hormone-releasing hormone	Growth-hormone-releasing factor, somatocrinin	GHRH, GHRF, GRF	arcuate nucleus neuroendocrine Neuroendocrine Neuroendocrine [IPA n??ro?'?nd?kr?n] cells are cells that release a hormone into the circulating blood in response to a neural stimulus. These hormones may be amines, neuropeptides, or specialized amino acids.... neurons	stimulates secretion of growth hormone Growth hormone Growth hormone is a peptide hormone. It stimulates human development and cell reproduction in humans and other animals. It is a 191-amino acid, single chain polypeptide hormone which is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland.... \|- \| Somatostatin Somatostatin Somatostatin is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G-protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones....	Growth hormone-inhibiting hormone, Somatotropin release-inhibiting factor	SS, GHIH, SRIF	neuroendocrine neurons of the periventricular nucleus Periventricular nucleus The Periventricular nucleus is a composite structure of the hypothalamus.It should not be confused with the paraventricular nucleus....	inhibits secretion of growth hormone Growth hormone Growth hormone is a peptide hormone. It stimulates human development and cell reproduction in humans and other animals. It is a 191-amino acid, single chain polypeptide hormone which is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland.... \|- \| Thyrotropin-releasing hormone Thyrotropin-releasing hormone Thyrotropin-releasing hormone , also called thyrotropin-releasing factor , thyroliberin or protirelin, is a tropic hormone peptide hormone that stimulates the release of thyroid-stimulating hormone and prolactin by the anterior pituitary....	Thyrotropin-releasing factor, Thyroliberin, Protirelin	TRH, TRF	parvocellular neuroendocrine neurons in the paraventricular Paraventricular nucleus The paraventricular nucleus is a neuronal nucleus in the hypothalamus. It contains multiple subpopulations of neurons that are activated by a variety of stressful and/or physiological changes.... and anterior hypothalamic nuclei Anterior hypothalamic nucleus The Anterior hypothalamic nucleus is a nucleus of the hypothalamus.Its function is thermoregulation of the body....	stimulates secretion of TSH Thyroid-stimulating hormone Thyroid-stimulating hormone is a peptide hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland.... \|- \| Vasopressin Vasopressin Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a hormone found in most mammals, including humans....	Arginine vasopressin, Antidiuretic hormone, Argipressin	AVP, ADH	parvocellular Parvocellular Parvocellular can refer to:* Parvocellular part* part of the Paraventricular nucleus of hypothalamus... neuroendocrine neurons in the paraventricular nucleus Paraventricular nucleus The paraventricular nucleus is a neuronal nucleus in the hypothalamus. It contains multiple subpopulations of neurons that are activated by a variety of stressful and/or physiological changes....	with Corticotropin-releasing hormone Corticotropin-releasing hormone Corticotropin-releasing hormone , originally named corticotropin-releasing factor , and also called corticoliberin, is a polypeptide hormone and neurotransmitter involved in the stress .... , stimulates secretion of ACTH Adrenocorticotropic hormone Adrenocorticotropic hormone is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress ....

Anterior pituitary

Regions

Embryology

Major hormones secreted

Hypothalamic releasing and release-inhibiting factors

Additional images

See also

External links