Adhesion Junctions Associated with Synapses and Dendritic Spines

by Josef Spacek

Fig. 1: A model of our suggestion how a synapse can enlarge in the process of synaptic plasticity. Ax - axon terminal; DS - dendritic spine; SA - spine apparatus; a material of the inner dense plate - in yellow; PA - punctum adherens-like nascent zone, free of synaptic vesicles; SAZ - the extending synaptic active zone.

Fig. 2: The hippocampal perforated spine synapse as it looks under the classical view of homogenious ultrastructure (A) and inhomogeneous ultrastructure (B) containing vesicle-free adherent puncta (yellow), vesicle-free transitional zones (nascent zones - blue) and vesicle-associated synaptic active zone (red). See Spacek and Harris, 1998 and Bell et al., 2014, for details.

Fig. 3: Catenin marked with immunogold particles in the punctum adherens-like nascent zone. (Human, cerebral cortex.)

Fig. 4: A punctum adherens (green) fixing an astrocyte process (pale blue) to a mushroom-shaped dendritic spine possesing a perforated synapse (red). The spine (A) and astrocyte (B) made semitransparent to enable the punctum to be visible.

Fig. 5: Reconstruction of extensively elaborated net-like vesicle-free adhesion junctions (yellow) associated with synaptic active zones (red) between a dendrite of thalamocortical relay neuron and a lemniscal giant axon terminal in thalamic ventrobasal nucleus of rat.