Dialysis blocks the passage of larger substances (for example, red blood cells, large proteins). This replicates the filtering process that takes place in the kidneys when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus. The two main types of dialysis, hemodialysis and peritoneal dialysis, remove wastes and excess water from the blood in different ways. Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite.
Subcommissural organ neuronal cell bodies within the subcommissural organ, although the specialized cells receive some innervation from outside neurons. Ependymal cells secrete high molecular mass glycoproteins into the cerebrospinal fluid, in which the bulk of them condense to form a filamentous structure named Reissner’s fiber. The subcommissural organ/Reissner’s fiber complex is thought to be involved in the reabsorption and circulation of the cerebrospinal fluid, and with functions related to electrolyte and water balance. One of the proteins secreted by the subcommissural organ, and which is present in Reissner’s fiber, is spondin. SCO-spondin is a “giant” (5000 amino acids) glycoprotein (thrombospondin superfamily) found