Walsh & Hoyt: Choroid Plexus Tumors

During embryogenesis, the cells that line the villi of the choroid plexus are initially similar to those that line the rest of the ventricular system, containing both cilia and blepharoplasts. By 22 weeks of gestation, however, the cilia and blepharoplasts disappear. The mature choroid plexus contains three main types of cells: cuboidal or columnar cells that line the villi of the choroid plexus (type I cells); flat cells that line connective tissue adjacent to neural tissue (type II cells); and flat cells that line crypts in connective tissue (type III cells). Tumors that derive from the choroid plexus may develop from any of these cell types.