SYNAPSE-LIKE CONTACTS BETWEEN INTRAVENTRICULAR AXONAL ENDBULBS AND APICAL PLASMALEMMA OF EPENDYMA (RABBIT)

In the 3rd and 4th ventricle of the brain (rabbit) a great number of non-myelinated axons are found having bulb like endings. These terminals contain small clear vesicles (400-800 Å), dense cored vesicles (650-1000 Å), and mitochondria, wich are characterized by a single prismatic tubule. The plasmalemma of the bulb is in a synapse-like contact with the apical plasmalemma of the ependyma. The contact is characterized by presynaptic dense bodies, membrane thickening, subjunctional bodies, and parallel intersynaptic filaments (50 Å) across the synaptic gap (200 Å). Besides, between the bulbs and ependyma desmosome-like junctions are found. © 1969 Springer-Verlag.