Final answer:
The 'Brain Under Construction' section explains the development of the brain during adolescence, relating embryonic structures to adult anatomy and detailing the formation of major brain regions.
Step-by-step explanation:
The section titled "Brain Under Construction" significantly contributes to the overall purpose of the text by explaining brain development during adolescence. This section facilities understanding of how the neural tube evolves into the primary vesicles and further into the major regions of the brain, namely the forebrain, midbrain, and hindbrain, as it transitions from the embryonic stage through to a fully developed adult brain. By detailing these developmental processes, the section helps readers relate embryonic structures to their adult counterparts, recognize the major regions of the adult nervous system, and understand the basis for cognitive functions and potential changes that occur during this pivotal developmental period.