Immuno-electron-microscopic analysis of the basal route of secretion in the subcommissural organ of the rabbit

Summary Low-temperature-embedded tissue of the subcommissural organ (SCO) of the rabbit was analyzed for the basal route of secretory product by means of indirect immuno-metal cytochemistry (protein A-gold technique) at the electron-microscopic level. By use of (1) an antiserum against bovine Reissner's fibre (see Sterba et al. 1981) and, thereafter, (2) particulate gold-marker solution, immunoreactive sites could be clearly visualized within the extracellular matrix of both (a) the basal part of the ependymal cell layer, and (b) the hypendyma proper. Abundant secretory material was identified within (i) dilated intercellular spaces (a + b) as well as (ii) branching basal lamina labyrinths and distinct perivascular spaces (b). All these compartments are thought to belong to a system of extracellular channels, which may function in secretion directed toward hypendymal blood vessels.Supported by Grants from the Ministry for Sciences and Technology of the German Democratic RepublicThe expert technical assistance of Mrs. S. Mehnert, Mrs. E. Siebert, Mrs. Ch. Schneider, Mrs. I. Seifert and Mr. H. Wolf is gratefully acknowledgedDedicated to Prof. Dr.Dr.h.c. Andreas Oksche on the occasion of his 60th birthday