Analysis of the Secretory Products of the Subcommissural Organ

The subcommissural organ

“…Ultrastructural immunocytochemistry using polyclonal and monoclonal antibodies has demonstrated strong labeling of the secretory material located in the dilated RER cisternae (Figs. 15, 16) and the secretory granules located at the apical cell pole (Grondona et al, 1994b;Lösecke et al, 1984;Pérez et al, 1995;Peruzzo et al, 1990;Rodríguez et al, 1986Rodríguez et al, , 1987a and in the vascular and leptomeningeal ependymal endings Rodríguez et al, 1987b). There are monoclonal antibodies that react with the secretory granules but not with the RER content .…”

“…(From Rodríguez et al, 1984a). et Rodríguez et al, 1987a) and in the perivascular space proper (Lösecke et al, 1986). RF-immunoreactive material has been detected within transcytosis vesicles of the endothelial cells of the dog SCO (Peruzzo, 1995).…”

“…All these findings support the view that the SCO secretes into the blood a material that is recognized with anti-RF sera. However, in the dog SCO there are numerous perivascular secretory cells containing granules that are not reactive with anti-RF sera (Peruzzo, 1995;Rodríguez et al, 1987a), suggesting that in this species the SCO would secrete into the blood a material different from RF glycoproteins.…”

“…The content of the granules and the RER is immunoreactive with antibodies specific for the SCO secretion (Figs. 15,16) (Rodríguez et al, , 1987a. There are conspicuous species variations in the number, size, shape, and inner structure of the secretory granules located in the ventricular cell pole (for references, see Rodríguez et al, 1992).…”

“…Con A identifies N-linked glycoproteins; LFA identifies glycoproteins that have not passed (negative binding) or that have passed (positive binding) through the Golgi apparatus. This type of analysis and the raising of antibodies against each of the three major compounds of the bovine SCO (540, 450, and 320 kDa) and the use of these antibodies in a comparative immunocytochemical study have allowed us to draw some important conclusions (Hein, 1988;Hein et al, 1993;Nualart et al, 1991;Rodríguez et al, 1987aRodríguez et al, , 1992. (1) The 540-and the 320-kDa immunoreactive glycoproteins are, in all probability, precursor forms because they bind Con A but not LFA and they are present in the SCO and missing in RF.…”