[Ultrastructural changes in the sensorimotor area of the hindbrain archistriatum in the chick embryo during motor avoidance of electrodermal stimulation].

Controlled and uncontrolled stimulation of the motor activity of 18-day chick embryo induces ultrastructural changes in sensomotor region of the archistriatum. These changes include the increase in the bulk of membrane structures, the increase of the area of presynaptic regions, the increase in electron density of microtubules and neurofilaments. Formation of a new adaptive behaviour is accompanied by an increase in the number of active synapses, which presumably accounts for adaptive plasticity of the brain in embryogenesis.