Pineal gland (Endocrinology)
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The document presents information about the pineal gland, an important endocrine gland located in the brain, known for its pinecone-like structure and its role as the 'third eye' due to its connection to vision. It details the anatomy and histology of the gland, including the two main types of cells: pinealocytes and astrocytes, and their functions, particularly in the secretion of melatonin, which regulates sleep, biological rhythms, and various physiological functions. The content highlights the gland's historical discovery and embryological origin, emphasizing its significance in higher vertebrates.
Pineal gland (Endocrinology)
- 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.
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