Question

The cavity of the brain is lined by
A. Neural epithelium
B. Ependymal epithelium
C. Cerebrospinal fluid
D. Glandular epithelium

Answer 1

Hint: The brain has a set of internal cavities called the ventricular system. Four different ventricular cavities are present at the centre of the brain which extends down to the spinal cord. These cavities are lined by a special type of cell.

Complete answer:
The brain consists of a set of cavities known as the ventricles. There are 4 ventricular cavities within the brain that are present exactly at the centre of the brain and extend down to the spinal cord. These ventricles possess the choroid plexus. The choroid plexus is the clump of cells that produces the cerebrospinal fluid which is circulated throughout the cranial cavity and even down the spinal cord. These cavities are lined by a special type of epithelial tissue called the ependymal cells.

The ependymal cells are tissues that possess many tight junctions and serve as a barrier between the blood and spinal fluid. This barrier is known as the blood-CSF barrier and prevents any pathogenic or non-essential cell from entering the CSF. This is of vital importance as any pathogen or unwanted toxin enters the CSF may affect the brain. The CSF produced in these cavities is constantly reabsorbed and recirculated. Thus any unwanted substance which diffuses through the blood into the fluid would render the brain vulnerable to pathogenic attack or exposure to toxins.

Therefore, the correct answer is option B.

Note: There are 4 cavities and in each cavity, the CSF is produced by the choroid plexus.
The neural epithelium lines the neurons within the brain and the glandular epithelium lines the pineal gland, the hypothalamus, and the pituitary glands. The cerebrospinal fluid lines the cranial cavity. This fluid occupies the space between the brain and the skull.