Complex sentence: The subcommissural organ (SCO) is a small secretory organ located near the anterior entrance of the Sylvian aqueduct and at the midline roof of the third ventricle.
Split into simpler sentences: The subcommissural organ (SCO) is a small secretory organ located near the anterior entrance of the Sylvian aqueduct. It is also placed at the midline roof of the third ventricle.