Electron microscopic study of the porcine choroid plexus epithelium

The choroid plexus (CP) is a highly vascularized organ in the brain ventricles which acts as the main producer of cerebrospinal fluid (CSF). A study of the surface ultrastructure of the porcine CP was performed using scanning and transmission electron microscopy. The vascular walls of the capillaries were fenestrated. Epiplexus cells of different morphology were abundant on top of the epithelial surface. Two types of epithelial cells were present, characterized by the presence or absence of microvilli. Some epithelial cells contained cilia while other cells had large secretory protrusions called blebs. In the choroid epithelium of the lateral ventricles, some cells with large depressions were present. Cells with peduncles, such as recently discovered in the buffalo, could not be recognized. The variability of the choroidal surface structures clearly indicates the active role of the CP in the formation and maintenance of the CSF and its components.