A quantitative Golgi analysis of the postnatal maturation of dendrites in the central nucleus of the inferior colliculus of the rat.

In this work, we used Golgi impregnation and computer assistance to analyze the quantitative development of the dendrites of neurons in the central nucleus of the inferior colliculus in the rat from 8 (P8) to 20 (P20) days of age, i.e., during the period of functional maturation of the auditory system. The number and length of the dendritic segments and the number of spines of a total of 516 impregnated cells were studied. The variations of both the mean number of peripheral dendritic segments and the mean dendritic domain area suggest that the dendritic tree of these cells is orientated preferentially in the sagittal plane before the onset of functional maturation, but undergoes a reorientation in the frontal plane during this critical period. The length of dendritic segments varies as a function of both the stage of the period of functional maturation and the order of magnitude of these segments. During the first stage, from P8 to P16, only proximal and intermediate segments lengthen, the distal segments increasing their length later from P16 to P20. The lengthening of the dendritic segments is associated with dramatic reabsorption of the dendritic spines on all dendritic segments and seems closely related to the functional maturation of the auditory pathways.