Pineal gland ( Anatomy)
It is small reddish body resembling like pine cone derived from roof plate of diencephalon. It is situated in posterior aspect of third ventricle & separated from splenium( part of corpus callosum) by tela choroidea.
In humans, pineal body measures 8-10mm in length. This gland consists of two types of cells pinealocytes and neuroglial cells.Besides these, calcareous granules known as “ brain sand” is also present in gland which are radio-opaque and can be seen on X- Rays. Calcification occurs after 16 years of age.
Function
It secretes hormone called melatonin. Precursor for melatonin is serotonin which is derived from the amino acid tryptophan.
Effects of melatonin on reproduction and sleep.
1. On reproduction
Melatonin is anti-gonadotrophic in action so it inhibits gonadotrophin releasing hormones from hypothalamus thereby inhibiting secretion of luteinizing and follicle stimulating hormones from anterior pituitary. Melatonin secretion is indirectly proportional to length of day. So insects breed more in summer as compared to winter. Tumour of pineal gland may cause precocious puberty.
2. On sleep and activities
Its been found that melatonin levels are quite lower in insomniacs. Melatonin therapy seems helpful in correcting problem.
More summaries about the Pineal Gland Even Controls Pituitary Gland