The pineal gland, also known as the pineal body or epiphysis cerebri, is a small endocrine gland located in the brain between the two hemispheres. It produces the hormone melatonin, which modulates sleep patterns and seasonal cycles. Nearly all vertebrate species have a pineal gland. In humans, the pineal gland is reddish-gray and rice-sized, and it plays a role in inhibiting sexual development in children by regulating melatonin production. The primary function of the pineal gland is to produce melatonin, which controls seasonal fertility in some animals but plays little role in regulating sexual function in humans.

2. The pineal glands is also known as the pineal body, conarium or epiphysis cerebri.
It is small endocrine gland in the vertebrate brain.
The shape of the gland resemble a pine cone.
The pineal gland is located epithelium, near the center of the brain, between the two
hemispheres, tucked in a groove where the halves of the thalamus join.

3. The pineal gland produce melatonin, a serotonin derived hormone which modulates sleep
patterns in both circadian and seasonal cycle.
Nearly all vertebrate species possess a pineal gland.

5. The pineal gland is the only midline brain structure that is unpaired.
It takes its name from its pine-cone shape.
The gland is reddish-gray and about the size of grain of rice (5-8 mm) in humans.
It is part of the epithalamus and lies between the laterally positioned thematic bodies and behind the
habenular commissure.
It is also located behind the third ventricle & is bathed in cerebrospinal fluid supplied through a small
pineal recess of the gland.

6. Pineal
Gland

7. Unlike most of the mammalian brain, the pineal gland is not isolated from the body by the
blood brain barrier system.
It has profuse blood flow, second only to the kidney supplied from the choroidal braches of
the posterior cerebral artery.

8. The human pineal gland grows in size until about 1-2 years of age, remaining stable there
after although it’s weight increases gradually from puberty onward.
The abundant melatonin levels in children are believed to inhibit sexual development and
pineal tumor have been linked with precocious puberty.
When puberty arrives melatonin production is reduced.

9. The primary function of the pineal gland is to produce melatonin.
It controls the sexual activities in animals by regulating the seasonal fertility however, the
pineal gland plays little role in regulating the sexual function in human being.

10. SOURCE OF SECRETION :-
Melatonin is secreted by the parenchymal cells of pineal gland.
CHEMISTRY :-
Melatonin is an indole
( N-acetyl-5-methoxytryptamine).

11. ACTION OF MELATONIN :-
Melatonin acts mainly on gonads.
It’s actions differs from species to species.
In some animals it stimulates the gonads while in other animals, it inhibits the
gonads.
In humans it inhibits the onset of puberty by inhibiting the gonads.