idea that the abnormal and dysfunction of the sco precedes the development of the hydrocephalus. other disease it is reported that in spontaneously hypertensive rats there is a relation between sco and hypertension due to changing in its secretor activity and protein composition. history in 1860, ernst reissner, anatomist at the university of dorpat, published a monograph on the microscopic structure of the spinal cord of petromyzon fluviatilis. he described a string of 1.5 μm in diameter characterized by its high refringence, its extremely regular shape, and its lying free within the central canal. in 1866, karl kutschin confirmed reissner’s observations and named the fibrous structure reissner’s fiber. edinger (1892) described, in sharks, what later was known as “the subcommissural organ”. studnicka (1900), called attention to uncommonly tall ependymal cells covering the posterior comissure of p. fluviatilis. sargent, also in 1900, establishes the basis of what is presently regarded as the subcomissural organ – reissner fiber complex. finally, in 1910, dendy and nicholls introduce the term “subcommissural organ” to describe this brain gland. the rich vascularization of the sco was first reported by pesonen (1940). in 1958, helmut hofer postulated that this organ, despite its structural and functional differences from other circumventricular organs, is a highly secretory component of the circumventricular organ system.