The pituitary gland, known as the master gland, regulates various endocrine functions through hormones secreted from its anterior, posterior, and intermediate lobes. The anterior lobe releases several hormones critical for growth, metabolism, and reproduction, while the posterior lobe stores and secretes oxytocin and vasopressin, which are produced in the hypothalamus. Disorders of the pituitary, such as tumors and hormone imbalances, can lead to significant health issues, including Cushing's syndrome and diabetes insipidus.

1. Pituitary Gland
STRUCTURE | HARMONES |FUNCTIONS
Yousaf Rafique | Endocrinology | Date
M.Sc. (self) | Roll No. 24

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Pituitary Gland (Hypophysis):
The pituitary gland, a ductless endocrine gland, also known as hypophysis or the
master gland because its secreted hormones regulate other endocrine glands. It is present
below the hypothalamus in forebrain and behind the bridge of our nose. It is present close
to hypothalamus and are interconnected by a stalk called infundibulum. It is small, oval-
shaped and weighs about to 0.5 grams. Its size is about to 1/3 of an inch just like pea grain.
A bony cavity called “Sella turcica”, surrounds it. Body changes are detected by
hypothalamus and a stimulus is sent to the pituitary gland to produce difference
hormones and recovery is done by negative feedback mechanism.
In many species, it is partitioned into three lobes, i.e., anterior, intermediate and
posterior lobe. In humans, intermediate lobe is absent, and its cells found dispersed in
anterior lobe. The anterior lobe is also called adenohypophysis while posterior lobe is
called neurohypophysis. The anterior pituitary controls many of the physiological
processes like reproduction, growth, lactation and stress. The intermediate lobe secrets
melanocyte-stimulating hormone which regulates the color pigmentation in skin and hair
in rodents, mice, rats etc. The posterior lobe store and secretes the oxytocin and
vasopressin but not synthesis them by self.
The description of structures and functions of these lobes is given below:
ANTERIOR PITUITARY LOBE OR ADENOHYPOPHYSIS
Evagination of buccopharyngeal membrane called rathke’s pouch, forms anterior
pituitary lobe. The anterior pituitary lobe is sometimes divided into two parts. i.e. pars
tuberalis and pars distalis. These two parts make up the 80% of the gland. Another part,
called pars intermedia is present between these two parts and is more developed in
species other than human (in humans, it is rudimentary).
The anterior pituitary lobe consists of five different cells which make up different
type of hormone or hormones. Name of these five types of cells are:
• Thyrotropin
• The gonadotrophs
• The corticotrophs
• The somatotrophs
• Lactotrophs

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The hormones released by the anterior pituitary lobe are trophic and tropic which
are given in following table:
Name Functions
1. Follicle stimulating
hormone (FSH)
2. Luteinizing
hormone
3. Adrenocorticotropic
hormone (ACTH)
4. Thyroid-stimulating
hormone
5. Prolactin
6. Growth hormone
(GH)/
Somatotropin
− This hormone is found in testis and ovaries &
releases under the effect of gonadotropin-
releasing hormone (GnRH). This stimulates the
production of estrogen and increases the growth
of egg cell (ova) in ovaries in women & sperm cells
in testis of man.
− This hormone is also targeting the testis and
ovaries & releases under the influence of
gonadotropin-releasing hormone (GnRH). It
stimulates the production of progesterone in
female and testosterone in male.
− This is polypeptide tropic hormone and stimulates
the adrenal glands to produce cortisol and other
androgenic hormones. Cortisol regulate the
metabolism & maintain the blood pressure and
blood sugar level at heathy level. This hormone
is released under the influence of hypothalamic
corticotropin-releasing hormone (CRH).
− This hormone is released under the influence of
hypothalamic thyrotropin-releasing hormone
(TRH) and is inhibited by somatostatin. This
hormone stimulates the thyroid gland to produce
thyroid hormone which is necessary for body
temperature, heart rate and metabolism.
− Its release is stimulated by hypothalamic TRH,
oxytocin, vasopressin etc. Prolactin is inhibited by
hypothalamic dopamine. It stimulates the milk
production in women.
− It is released under the influence of hypothalamic
growth hormone-releasing hormone (GHRH). It is
essential in early years to maintain healthy body
composition and it stimulates the growth and
physical development. Bones and muscles are its
primary targets and regulates the tissue’s growth.
It also effects the height of a person and inhibited
by somatostatin. It also helps in healing the
wounds.

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POSTERIOR PITUITARY LOBE OR NEUROHYPOPHYSIS
The post pituitary lobe is made from the extension of hypothalamus. It is mainly
composed up of extensions of processes or exons, came from two pairs of large cluster
nerve cell bodies (nuclei) of hypothalamus. Hormones of posterior pituitary are
synthesized by these cell bodies. These nuclei are categorized into two types i.e.
Superaoptic nuclei which are present above the optic tract and Paraventricular nuclei
located on each side of third ventricle of brain. These nuclei, nuclei formed by the axons
of cell bodies of nerves and posterior pituitary gland’s nerve ending make up the
neurohypophaseal system.
Location and role of hypothalamus and pituitary gland
The hormones of posterior pituitary glands are produced in hypothalamus and
stored in it until their liberation. Hormones of posterior pituitary lobe are oxytocin and
vasopressin or antidiuretic hormone (ADH) and their functions are given in following
tables.
Name Functions
1. Oxytocin
2. Vasopressin
− It is released by paraventricular nuclei of
hypothalamus. Oxytocin stimulate the production of
breast milk in woman and the contraction of uterus
during child’s birth.
− It is also called antidiuretic hormone (AGH) or
arginine vasopressin (AVP). It is released from the
supraoptic nuclei in hypothalamus. It prevents
dehydration and helps body to conserve water by
stimulating the kidneys to increase the water
reabsorption in blood by acting on collecting ducts.
ADH is stimulated in less amount of serum osmolality
which is a sign of dehydration.

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INTERMEDIATE PITUITARY LOBE
It is present adjacent to the neurohypophysis in most vertebrates and is not
distinctive structure in adult human but prominent in human fetus rats, dogs and
monkeys. It makes the contact between the anterior and posterior pituitary gland.
It is composed up of endocrine cells called melanotrophs which secretes
melanocyte-stimulating hormone (MSH) and beta-endorphin which stimulates the
production of m. MSH are also synthesized in anterior lobe and are called intermedins
when released by intermediate lobe.
DISEASES AND DISORDER OF PITUITARY GLAND
Function and structure of pituitary gland can be affected by several conditions
like tumor around it can impact the release of its hormone. The diseases associated with
pituitary gland are given below:
▪ Pituitary tumors: It affects the hormone to be released but is noncancerous. It can
affect the other parts brain leading to headache or vision problems. There are two
types of pituitary tumors i.e. secretory in which too much secretion of a hormone
occurs and non-secretory in no secretion occur of hormone.
▪ Hypopituitarism: It is the condition in which the low or no secretion occurs of one
or more hormones. Effects of it are even fatal and can affect the growth,
reproductive system and adrenal secretion.
▪ Acromegaly and Hyperpituitarism: The condition in which over secretion of one or
more hormone occur is called hyperpituitarism while if the over production of
growth hormone is called acromegaly. Acromegaly can lead.to excessive growth
mostly hands and feet.
▪ Cushing’s Syndrome: The over secretion of ACTH leads to disease called Cushing’s
syndrome or disease. It can cause high blood pressure, weight gain and weakness.
▪ Hyperprolactinemia: The over production prolactin in blood is called
hyperprolactinemia which leads to infertility and decreased sex drive.
▪ Central diabetes insipidus: Excessive production or secretion of vasopressin leads
to diabetes insipidus.
References:
1. https://en.wikipedia.org/wiki/Pituitary_gland
2. https://www.britannica.com/science/pituitary-gland
3. https://www.endocrineweb.com/endocrinology/overview-pituitary-gland
4. https://www.healthline.com/human-body-maps/pituitary-gland#conditions
5. https://www.ncbi.nlm.nih.gov/pubmed/1717055
6. https://www.ncbi.nlm.nih.gov/pubmed/1717055
7. https://www.sciencedirect.com/topics/neuroscience/pars-intermedia