The structure surrounding the pineal gland in the forebrain is located at:

....... plays a very important role in the regulation of a $24$ hours rhythm of our body.

Which hormone relates with temperature and sleep-wake cycle?

The organ which was considered vestigial until recently but is now confirmed to be an endocrine gland is:

Which gland plays a very important role in the regulation of the $24$-hour (diurnal) rhythm of our body?

$P$ is a small,round,reddish structure located on the dorsal side of the forebrain. It contains a stalk and releases a hormone $Q$ which controls the diurnal rhythm of the body. $P$ and $Q$ are