Structural changes in the area striata of the mouse after enucleation

Summary The optic pathways of the mouse have been studied by tracing of degenerating fibers after enucleation and coagulation of the lateral geniculate nucleus. The effects of unilateral enucleation at birth in the contralateral area striata of the mouse have been studied with the Golgi method. The number of spines on three different portions of the apical dendrites of layer V pyramidal cells have been counted in the affected area striata of mice 24 and 48 days old enucleated at birth. The results were compared with the countings obtained in the area striata homolateral to the enucleated side and with controls of the same ages. The results indicated that enucleation produces, through a series of transneuronal changes, significant diminution of the number of spines in the apical dendritic segments located in layer IV. The diminution of dendritic spines is more pronounced in younger animals. Specific variations in the orientation of dendrites of stellate cells with ascending axons have been observed in enucleated animals. The significance of these findings has been discussed suggesting the existence of compensatory mechanisms which affect significantly the intrinsic organization of the area striata.