|
Reissner's fiber is a fibrous aggregation of secreted molecules extending from the subcommissural organ (SCO) through the ventricular system and central canal to the ampulla caudalis, a small ventricle-like structure at the end of the spinal cord.〔 〕 In vertebrates, Reissner's fiber is formed by secretions of SCO-spondin from the subcommissural organ into the spinal fluid of the ventricular cavity. 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. ==Structure== Reissner’s fiber (RF) is a complex and dynamic structure present in the third and fourth ventricles and in the central canal of the spinal cord, observed in almost all vertebrates, except in humans and anthropoid apes. It is formed by the assembly of complex and variable high weight molecular glycoproteins secreted by the SCO that are released to the cerebrospinal fluid. At least five different proteins were found, of 630 kDa, 480 kDa, 390 kDa, 320 kDa and, the major constituent, 200kDa that is present in both RF and cerebrospinal fluid, CSF. One of the most important RF-glycoproteins secreted by the SCO has been named SCO-spondin and is of major importance especially during embryonic life. Reissner’s fiber grows caudally by the addition of those glycoproteins at its cephalic end and extends along the brain aqueduct (Aqueduct of Sylvius), and the entire length of the central canal of the spinal cord, growing continuously in the caudal direction. It is just a small part of the secretions made by SCO and remains a matter of speculation, probably involved in many physiological functions as clearance of monoamines, detoxification of the CSF, neuronal surviving or the control of water balance.〔 The glycoproteins forming RF can be found in three conformations, the first on is when the material aggregates over the SCO cilia, the so-called pre-RF, the second and most studied form known as the proper RF which is a cylindrical regular structure, and finally a third and final form, massa caudalis, known as the final distribution and the final assembly of the proteins.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Reissner's fiber」の詳細全文を読む スポンサード リンク
|