___Tissue found in the brain, spinal cord, and peripheral nerves. The basic cells are the___ Types of Membranes ___ membranes (3 types are A. ___ line the body cavities that do not open to the outside, reducing friction between organs and cavity walls, and secrete serous fluid, B. ___ line the cavities of epithelial and underlying connective tissues.) Some membranes are composed entirely of connected tissue include ___ and___ Solution The epithelial cells are the outermost cells. They have nerve supply but no blood supply. These cells receive nutrition from substances diffusing from the underlying blood vessels.Below the epithelial cells is the basement membrane which provides nutrition and new epithelial cells arise from the basement membrane..