Ultrastructural immunocytochemical study of the massa caudalis of the subcommissural organ-Reissner's fiber complex in lamprey larvae (Geotria australis): Evidence for a terminal vascular route of secretory material

The subcommissural organ

“…27, 29) (Hofer et al, 1984;. RF-immunoreactive material has been detected by ultrastructural immunocytochemistry in all these cavities, including the local blood capillaries (Peruzzo et al, 1987). This finding gives strong support to previous studies suggesting the passage of RF material from the ampulla to local blood vessels (Hofer, 1964;W.…”

“…Already in cyclostomes, either lampreys or hagfish, the SCO-RF complex presents the basic characteristics found throughout the vertebrate phylum, namely, tall ependymal cells displaying dilated RER cisternae and secreting into the ventricle, hypendymal cells projecting to the leptomeninges, and an RF extending along the central canal and ending as a distinct massa caudalis, from where the RF material escapes through openings in the dorsal wall of the ampulla to reach the local blood vessels (Adam, 1957;Hofer et al, 1984;Peruzzo et al, 1987;Sterba, 1962;Sterba et al, 1967a). Invertebrate chordates lack an SCO but possess an RF, a phenomenon that raises the question of the source of RF material in these species (Olsson, 1993).…”

“…When reaching the terminal ventricle, RF glycoproteins undergo some chemical changes and form a gel mass, known as massa caudalis (Oksche, 1969;Olsson 1958a,b). These glycoproteins escape through the dorsal wall of the terminal ventricle to reach local blood vessels (Peruzzo et al, 1987).…”

Human subcommissural organ, with particular emphasis on its secretory activity during the fetal life

“…Already in cyclostomes, the SCO-RF complex presents the basic characteristics found throughout the vertebrate phylum, namely, tall ependymal cells displaying dilated RER cisternae and secreting into the ventricle high molecular weight glycoproteins that assemble to form Reissner's fiber (RF), and a RF growing along the central canal and ending as a massa caudalis, from where the RF-glycoproteins escape through openings in the dorsal wall of the ampulla to reach the local blood vessels (Adam, 1957;Hofer et al, 1984;Molina et al, 2000 [this issue]; Peruzzo et al, 1987;Sterba, 1962;Sterba et al,1967). In addition, basal processes of ependymal and hypendymal cells project to the highly vascularized leptomeninges, establishing a second route carrying secretory material.…”

Functional aspects of the subcommissural organ-Reissner's fiber complex with emphasis in the clearance of brain monoamines

“…When RF reaches the caudal end of the central canal, the RFmaterial becomes unpacked and forms an irregular mass of secretory material known as massa caudalis (Hofer, 1964;Olsson,1955). At this level, the RF-material is assumed to undergo some chemical modification (S. Rodríguez et al, 1987) to finally reach local blood capillaries (Peruzzo et al, 1987). Thus, RF can be regarded as a result of a dynamic process involving various mechanisms such as: pre-packaging, packaging, and unpacking of the secretory molecules; shift of the secretory material along the fiber structure, and chemical modifications of the RF-molecules when arriving at the distal end.…”