This gland lies near the centre of the brain (see fig. II).
It if very small, not much larger than a grain of wheat.
An important effect of the pineal secretions is to inhibit the gonads' activity, thus holding sex in abeyance, during childhood. Later on, it aids in the maturing processes of sex after pubeity. Some experimental evidence indicates that pineal hormones inhibit ACTH secretion and thus indirectly help to regulate the secretions of the adrenal gland.