[Histological changes in the somatosensory thalamus after unilateral coagulation of vibrissa follicles of the muzzle of the newborn mouse].

Light microscopic study of the thalamic ventro-basal complex (VB), after unilateral coagulation of vibrissae follicles in newborn mouse, revealed an excess of neuronal perikarya on the controlateral "deafferented" side as compared to the normal side. The higher density of nerve cells was confined to the vibrissal relay in the medial part of VB nucleus (VBm), whereas the cell number in the non vibrissal-lateral part of this nucleus (VB1) remained on the control level. Electron microscopic investigation of the thalamic vibrissal relay has shown signs of a modified synaptogenesis on the "deafferented" side: (a) the number of specific afferents has diminished and in contrast to the normal side, most of the specific sensory terminals contain small spheroid synaptic vesicles and (b) the number of axon terminals with ovoid pleomorphic vesicles has been doubled.