Final answer:
The statement is true; the forebrain/prosencephalon differentiates into the telencephalon, which becomes the cerebrum, and the diencephalon, leading to structures such as the thalamus and hypothalamus.
Step-by-step explanation:
The statement that the forebrain/prosencephalon (primary vesicle) matures into the telencephalon and diencephalon (secondary vesicles) is True.
During the development of the embryonic brain, the neural tube enlarges into three primary vesicles: the prosencephalon (forebrain), the mesencephalon (midbrain), and the rhombencephalon (hindbrain). As development progresses, the prosencephalon differentiates further into two secondary vesicles: the telencephalon and the diencephalon. The telencephalon goes on to become the cerebrum, the main part of the human brain, while the diencephalon develops into adult structures like the thalamus and hypothalamus and retains its embryonic name due to its placement and function as a through-region between the cerebrum and the rest of the nervous system.
Also noteworthy is that a structure known as the eye cup emerges from the embryonic diencephalon and eventually becomes the retina, illustrating a unique case of nervous tissue that develops as part of the central nervous system (CNS) in the embryo and becomes a peripheral structure post-development.