1. The pineal gland is a small endocrine gland located at the center of the brain.
松果腺是位于大脑中心的一种小型内分泌腺体。

2. The pineal gland produces the hormone melatonin, which regulates the sleep-wake cycle.
松果腺产生的激素褪黑激素调节睡眠-清醒周期。