posterior pituitary

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1. pertaining to the pituitary gland.
3. a preparation of the pituitary glands of animals, used therapeutically.
pituitary gland an endocrine gland located at the base of the brain in a small recess of the sphenoid bone called the sella turcica. It is attached by the hypophyseal stalk to the hypothalamus and is divided into an anterior lobe (the adenohypophysis) and a posterior lobe (the neurohypophysis), which differ in embryological function and origin. Called also hypophysis.

The adenohypophysis originates from epithelial tissue. The adenohypophysis secretes six important hormones: growth hormone, thyroid-stimulating hormone or thyrotropin, adrenocorticotropic hormone or corticotropin, prolactin, follicle-stimulating hormone, and luteinizing hormone. Most of these hormones are tropic hormones, which regulate the growth, development, and proper functioning of other endocrine glands and are of vital importance to the growth, maturation, and reproduction of the individual. Secretion of the anterior pituitary hormones is controlled by releasing and inhibiting hormones produced by the hypothalamus. Information gathered by the nervous system about the well-being of an individual is collected in the hypothalamus and used to control the secretion of hormones by the pituitary gland. The hypothalamic releasing and inhibiting hormones are transported to the pituitary gland by way of the hypothalamic-hypophyseal portal system in which the hypothalamic venules connect with the capillaries of the anterior pituitary.

The neurohypophysis originates from neural tissue; it stores and secretes two hormones, oxytocin and vasopressin (antidiuretic hormone). These hormones are synthesized in the cell bodies of neurons located in the hypothalamus and transported along the axons to the terminals located in the neurohypophysis and are released in response to neural stimulation.

Surgical removal of part or all of the pituitary gland is called hypophysectomy and is usually done for treatment of a pituitary tumor. Because of its influence on the adrenal cortex and other endocrine glands, removal of the pituitary gland has widespread effects on the body. See hypophysectomy.
The pituitary gland and its relationship to the hypothalamus.
posterior pituitary neurohypophysis.

pos·te·ri·or pi·tu·i·tar·y

the cleaned, dried, and powdered posterior lobe obtained from the pituitary body of domestic animals used for food by humans; an oxytocic, vasoconstrictor, antidiuretic, and stimulant of intestinal motility.

posterior pituitary

not itself the site of hormone synthesis, but the site of release of hormones formed in the hypothalamus by neurons whose axons form the hypophyseal-pituitary tract, store the hormones in their terminals, and release them into the blood stream in response to action potentials (neurohormones: compare adrenal medulla). antidiuretic hormone ( syn vasopressin ) regulates water loss in the kidneys, by increasing water retention; oxytocin stimulates uterine contractions and the ejection of milk from the breasts. See also hormones; Table 1.
Table 1: Hormones
Site of productionName of hormoneMain targetsInvolved in regulating:Secretion controlled by:
HypothalamusReleasing and inhibiting hormonesAnterior pituitary (via local blood vessels)Secretion of anterior pituitary hormonesOther brain regions; feedback re regulated hormones and their actions
Neurohormones released from posterior pituitary:
OxytocinUterus, breastsLabour and lactationAfferent information from target organs
Antidiuretic hormone (ADH, vasopressin)KidneysWater loss: ECF volume and osmolalityHypothalamic osmoreceptors
Anterior pituitary(Human) growth hormone (H)GHMost cellsGrowth and metabolismHypothalamic releasing and inhibiting hormones via local blood vessels
ProlactinBreastsMilk production
Trophic hormones:
Thyroid-stimulating (TSH)Thyroid glandThyroid secretions
GonadotrophinsOvary or testisGerm cell maturation and hormone secretions
Adrenocorticotrophic (ACTH)Adrenal cortexCortisol secretion
Pineal bodyMelatoninWidespread, including brain, thymus, etc.
  • Sleep/wake cycle
  • Antioxidant
  • Immune system
Hypothalamus; varying light input from retina
  • Thyroxine
  • Triiodothyronine
  • Calcitonin
  • Most cells
  • Bone, kidneys, gut
  • Cellular oxidative metabolism
  • Decreases ECF [Ca2+]
  • TSH from anterior pituitary. Negative feedback from blood hormone concentration
  • ECF [Ca2+]
ParathyroidsParathormoneBone, kidneys, gut
  • Calcium and phosphorus absorption, secretion and turnover in bone.
  • Increases ECF [Ca2+]
ECF [Ca2+]
Adrenal: Cortex
  • Cortisol
  • Aldosterone
  • Androgens
  • Most cells
  • Kidneys
  • Gonads & other tissues
  • Metabolism
  • Response to stress
  • Na and K balance
  • Sex characteristics and reproductive function
  • ACTH from anterior pituitary
  • ECF [Na+] [K+]
  • Renin-angiotensin
  • ACTH
  • Adrenaline
  • Noradrenaline
Heart, smooth muscle, glandsCardiovascular and metabolic adjustments to activity and stressSympathetic nervous system
Atrial wallAtrial natriuretic hormoneKidneysBlood volume; increases sodium (therefore also water) loss in urineStretch of atrial wall by venous pressure
Gonads: TestisAndrogens (mainly testosterone)Genitalia and other tissuesReproductive function and sex characteristicsAnterior pituitary gonadotrophins
  • Oestrogens
  • Progesterone
Uterus, breasts and other tissuesMenstrual cycle, pregnancy, lactation
  • Insulin, glucagon
  • Somatostatin
  • Most cells
  • Other secretory cells in the pancreas
Blood levels, storage and cellular uptake of nutrients, notably glucose, but also proteins and fatsBlood levels of nutrients; autonomic nervous system; other gastrointesinal hormones
Alimentary tract
StomachGastrinGastric acid-secreting cellsGastrointestinal functions: motility, digestive juices and other secretionsLocal chemical and mechanical factors in the alimentary tract
Small intestine
  • Secretin
  • Cholecystokinin- pancreozymin (CCK-PZ)
  • Somatostatin, motilin
  • Other peptide hormones including vasoactive intestinal peptide (VIP)
  • Widespread on
  • GI tract
Several GI functions including bile flow, pancreatic enzyme and exocrine secretionsIngestion of food, distension of GI tract


1. a neuroepithelial endocrine gland of dual origin at the base of the brain in the sella turcica, attached by a stalk to the hypothalamus; called also hypophysis. It is composed of two main lobes, the anterior lobe (anterior pituitary, adenohypophysis), secreting several important hormones that regulate the proper functioning of the thyroids, gonads, adrenal cortex, and other endocrine glands, and the posterior lobe (posterior pituitary, neurohypophysis) whose cells serve as a reservoir for hormones having antidiuretic and oxytocic action, releasing them as needed, and in response to signals from the hypothalamus, itself responding to incoming signals from the nervous system received by the thalamus. Called also hypophysis. See also pituitrin, vasopressin, oxytocin, antidiuretic hormone, thyrotropin releasing hormone, adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone, melanocyte-stimulating hormone, prolactin and growth hormone.
2. pertaining to the pituitary gland.
3. a preparation of the pituitary glands of animals, used therapeutically.

pituitary abscess
abscess in the rete mirabile of the pituitary is recognizable clinically in cattle. The syndrome begins with a characteristic inability to close the mouth. Saliva drools, the tongue is prolapsed slightly, and there may be blindness, opisthotonos, loss of balance and recumbency.
pituitary-adrenal axis
the interactions between hypothalamus, pituitary and adrenal cortex, involving releasing factors, tropic hormones and negative feedback mechanisms.
pituitary alopecia
see growth hormone-responsive dermatosis.
pituitary cachexia
see pituitary cachexia.
pituitary dwarfism
congenital dwarfism with all parts properly proportioned. Affected animals are miniatures of normals. There is delayed bone development and epiphyseal fusion is retarded. It is inherited in cattle and German shepherd dogs. See also German shepherd dog dwarfism.
pituitary giantism
fetal pituitary hormones
in sheep, cows and goats fetal pituitary ACTH stimulates fetal adrenal cortisol production inducing in turn placental estrogen secretion. Hence fetal placental hormone is important in the induction of parturition.
pituitary hypoplasia
congenital absence (aplasia) or incomplete growth (hypoplasia) of gland. Occurs in one form of inherited prolonged gestation in cattle and in poisoning by the weed Salsola tuberculata var. tomentosa. It is an inherited trait in German shepherd dogs.
posterior pituitary
1. the posterior lobe of the pituitary gland; the neurohypophysis.
2. a preparation of animal posterior pituitary having the pharmacological actions of its hormones, oxytocin and vasopressin; used mainly as an antidiuretic in the treatment of diabetes insipidus and as a vasoconstrictor.
pituitary rete mirabile abscess
see pituitary abscess.
pituitary tumor
includes adenoma, carcinoma and craniopharyngioma. All cause pressure on surrounding tissue and some cause endocrinological disturbances.


directed toward or situated at the back; opposite of anterior. In quadrupeds usually applied only to parts of the head.

with the x-ray beam passing from the back to the front, especially to the limbs.
posterior chamber luxation
see lens luxation.
posterior (caudal) drawer sign
instability of the stifle joint with caudal movement of the proximal tibia in relation to the distal femur; normally restricted by the intact posterior (caudal) cruciate ligament. This movement is used as a test in the diagnosis of rupture of the ligament in the dog.
posterior functional stenosis
failure of pyloric outflow from the abomasum, as part of the syndrome of vagus indigestion in cattle.
inherited posterior paralysis
congenital paraplegia recorded in cattle and pigs. There are other nervous signs, e.g. opisthotonos, in some forms.
posterior limiting membrane
posterior pituitary
posterior polar cataract
posterior segment
the vitreous body, retina, choroid and optic disk.
posterior station trypanosomes
one of the two types of cyclical development of trypanosomes. In this form the metacyclic trypomastigotes accumulate in the hindgut of the arthropod vector and are passed out with its feces. Infection of the definitive vertebrate host occurs via the skin or skin wound. Called also stercoracic.
posterior vena caval thrombosis
see caudal vena caval thrombosis.