[Changes in the ultrastructure and morphometric parameters of the cortical axospinal synapses as affected by a calcium-free medium].

Slice preparations of the white mouse sensorimotor cortex were examined for the morphometry of axospinal synapses in the material obtained under a standard experimental procedure and in sections perfused in calcium-free medium. The calcium-free medium in slice preparations was shown to reduce considerably the spine length and to increase the amount of spines with a negative curvature of the spine head in the contact area. Besides, it is noticed that the postsynaptic thickening grows, the active zone length decreases, the number of perforated contacts drops and the spine apparatus moves to the dendritic zone. It is supposed that the spine apparatus transfer is probably due to the reorganization of spine cytoskeleton, i.e., it is determined by both the motor activity of dendritic microtubules and the polymerization level of spine microfilaments.