Reissner's fiber

Reissner's fiber (named after Ernst Reissner) is a fibrous aggregation of secreted molecules extending from the subcommissural organ (SCO) through the ventricular system and central canal to the terminal ventricle, a small ventricle-like structure near the end of the spinal cord. In vertebrates, Reissner's fiber is formed by secretions of SCO-spondin from the subcommissural organ into the ventricular cerebrospinal fluid. Reissner's fiber is highly conserved, and present in the central canal of all chordates. In cephalochordates, Reissner's fiber is produced by the ventral infundibular organ, as opposed to the dorsal SCO.