Final answer:
The ventricles of the vertebrate brain contain cerebrospinal fluid (CSF), which is produced by ependymal cells in the choroid plexus.
Step-by-step explanation:
The ventricles of the vertebrate brain contain cerebrospinal fluid (CSF). The ventricles are remnants of the hollow center of the embryonic neural tube and are now open spaces where CSF circulates in the adult central nervous system. The meninges protect the brain and spinal cord, consisting of the dura mater, arachnoid mater, and pia mater, but it is within the ventricular system that the CSF is produced and circulated. The CSF is produced by the choroid plexus, which is comprised of ependymal cells that filter blood to create the CSF.
The continuous production and circulation of CSF provide cushioning for the brain, support chemical balance, and facilitate the movement of nutrients and waste products.