Final answer:
The central canal in the gray commissure of the spinal cord contains cerebrospinal fluid and links with the brain's ventricular system.
Step-by-step explanation:
The central canal in the gray commissure of the spinal cord contains cerebrospinal fluid (CSF) and is continuous with the ventricles of the brain. The CSF acts as a circulatory medium within the CNS, which is produced by ependymal cells in the choroid plexus by filtering the blood. Furthermore, the central canal is a remnant of the center of the neural tube and is integral in connecting the cerebrospinal fluid between the brain and spinal cord, ensuring the flow of CSF throughout the ventricular system.