- Also called as Epiphysis Cerebri
- The pineal gland is a pine cone shaped gland
of the endocrine system. - The Gland is conical, grey body measuring 5 to
8mm in length and 3 to 5mm in its greatest
width. - A structure of the diencephalon of the brain,
the pineal gland produces several hormones
including melatonin.
- Melatonin influences sexual development and
sleep cycles. The pineal gland is composed of
cells called pinealocytes and the cells of the
nervous system called glial cells. - The pineal gland connects the endocrine
system with the nervous system in that it
converts nerve signals from the sympathetic
system of the peripheral nervous system into
hormone signals.
Functions
- The pineal gland is involved in several
functions of the body including:- - Secretion of the hormone melatonin
- Regulation of endocrine functions
- Conversion of nervous system signals to
endocrine signals - Causes feeling of sleepiness
- Influences sexual development .
Histological organization
- Pia matter: the delicate inner layer of connective
tissue that surrounds the brain - Surrounding the pineal body
- Which functions as its capsule and which sends
connective tissue septa into the pineal body
subdividing it into lobules. - In the pineal we find two cell types,pinealocytes
(95% large light and round nuclei) and
astrocytes(glial cells,dark and elongated)
- Apart from cells the pineal gland also contains
sand— brain sand( corpora arenacea) - These are calcium containing concretions in
the pineal parenchyma, which increase in size
and number with age. These concretions are
radio opaque. - They don’t have any other function.
- Interstitial cells- cells of the second type found
amoung the pinealocytes and in greater
number in the stalk of the gland. - They have elongated nuclei.
- They resemble the astrocytes of the brain in
having long process and an abundance of
intermediate filaments throughout the
cytoplasm.
