Ependyma

Ependyma is a type of connective tissue cell (or neuroglia) in the central nervous system that forms an epithelial lining in the ventricular system. These cells, also called ependymocytes, create a barrier between blood and cerebrospinal fluid by being closely connected to each other through tight junctions. The basal ends of ependymal cells rest on a basement membrane (facing away from the ventricular cavity), while their apical sides face towards the ventricular cavity. They have cilia and microvilli on their apical side to help move cerebrospinal fluid within the ventricles.

When the folded layer of pia mater, along with its arterioles (known as the tela choroida), infringes into the ventricular cavity, it becomes enveloped by the ependymal lining. This combination is called choroid plexus, made up of the tela choroida (vascular pia) and ependyma (choroid epithelium). Ependymal cells in the choroid plexus have a cuboidal shape with cilia and microvilli on their apical side facing the ventricular cavity. As part of the choroid plexus, ependyma contributes to the production of cerebrospinal fluid.