A neurecto-epithelial cell that is part of the basal layer of the subcommissural organ and specializes in the secretion of proteins into the subarachnoid space. Hypendymal cells have similar characteristics to ependymal cells and express SCO-spondin. [ http://www.ncbi.nlm.nih.gov/pubmed/26778959 https://orcid.org/0000-0001-7258-9596 http://www.ncbi.nlm.nih.gov/pubmed/9579598 ]