Pineal Gland is a n important gland in higher vertebrates. It is also known as 'third eye' as this gland receives its stimuli through vision.

1. Presented by-
Nisha Arya
Kumaun University
M.Sc. 2nd Sem

2.  Pineal gland
 Anatomy of Pineal Gland
 Histology of Pineal Gland
1) Pinealocytes
2) Astrocytes
 Physiological Function
 References

3.  It is an important endocrine gland in higher vertebrates.
The name is derived from its pinecone like structure.
 It is also known as ‘third eye’ as this gland receives its
stimuli through vision.
 It was first discovered by Herophilus about 2000 years
ago.
 This gland is embryologically derived from
neuroectoderm of diencephalic roof.

4.  This gland is located on
the dorsal surface of
the brain.
 It is embedded in
between the cerebellum
and cerebrum.
 The shape is flattened
stalk like structure
hence it is called
epiphysis.
 it has sympathetic
innervation.

5.  Pineal gland consists of two types of major cells-
Pinealocytes and Astrocytes.
 Besides these connective tissue cells, mast cells, nerve fibre
etc. also present.
Structure of Pinealocytes

6. 1. It is a neuro secretory cell.
2. It has nucleated cell body like structure and also
possess short and long processes like neuron.
3. It is surrounded by plasma membrane which is
lipoprotein in nature.
4. It has prominent nucleolus and little RNA.
5. Free ribosomes are distributed in the cytoplasm.
6. Dendrite like two short processes present.

7.  Two types of Pinealocytes-
Light and Dark Pinealocytes
 light Pinealocytes are many and large cell types. Nucleus
is greatly lobulated. Cytoplasm is basophilic and is devoid
of glycogen. Ribosomes are more prominent.
 Dark Pinealocytes are few in number and comparatively
small in size. Nucleus is comparatively less lobulated.
Large amount of glycogen droplets present in the
cytoplasm.

8. Fig: Astrocytes
Features
Astrocytes present in between the
Pinealocytes.
 nucleus is elongated and dense
in nature.
 Have few mitochondria, Golgi
bodies, ER and ribosomes.
Occasional depositions of
glycogen droplets.

9.  Pineal gland secretes melatonin. It controls
sleepiness and wakefulness.
 Pineal gland controls the sex drive, hunger,
thirst and the biological clock which
determines the body’s normal aging process.

10.  www.biologydiscussion.com

11. THANK YOU