Question

Choroid plexus is a network of
A. Nerves
B. Muscle fibers
C. Capillaries
D. Lymph vessels

Answer 1

Hint: Choroid plexus is present in each ventricle of the brain. The choroid plexus produces cerebrospinal fluid (CSF), a colorless fluid found in the tissue surrounding the brain and spinal cord of all vertebrates. All of the four ventricles of the brain have a choroid plexus. The blood and cerebrospinal fluid are separated by a barrier which is composed of pairs of the membrane.

Complete answer:
The choroid plexus is made up of many capillaries, and separated from the ventricles by choroid epithelial cells. The cerebrospinal fluid is present which acts as a fluid filter. In this fluid the active transport of substances also takes place.There is also much active transport of substances into, and out of, the CSF as it is made.
The choroid plexus acts as a barrier in the brain which separates the blood from the cerebrospinal fluid (CSF), known as the blood-CSF barrier. Several growth factors are also secreted by choroid plexus which helps in maintaining the stem cell pool in the subventricular zone. Growth factors are necessary for successful brain development and also help in protecting against harmful microbes and toxins.
The choroid plexus is not made up of nerves but several nerves innervate the choroid plexus, for example a well-developed adrenergic and cholinergic innervation reaching both the secretory epithelium and the vascular smooth muscle cells.
Choroid plexus is not a network of Nerves, muscle fibers and lymph vessels, it is made up of a network of capillaries.

So, option C. Capillaries is the correct answer.

Note:
The blood-CSF barrier consists of a choroid plexus along with the arachnoid mater and creates a pair of membranes that separate the blood from the CSF. This barrier is composed of a combination of ependymal cells with tight junctions on its apical surface and a core of fenestrated capillaries surrounded by connective tissue. Tight junctions are made up of proteins and a network of claudins that serve as a checkpoint to limit the passage of substances between the cells. The choroid plexus has a role in iron homeostasis in the brain as it is a major source of transferrin secretion which helps in iron homeostasis.