Indagini sulle relazioni fra microambiente perineuronale e sviluppo delle propaggini del corpo dei neuroni dei gangli spinali del ratto

While the outgrowth of the slender projections from the perikaryon of spinal ganglion neurons is an intrinsic property of these neurons, it is also influenced by the surrounding microenvironment. To obtain evidence concerning whether the outgrowth of these projections is influenced by one or both components of the perineuronal microenvironment (satellite cells plus extracellular matrix) we have taken advantage of a rare arrangement of these neurons. In the spinal ganglia of adult animals nerve cell bodies are occasionally arranged in pairs, the two nerve cell bodies of the pair being separated by a satellite cell sheet lacking a basal lamina, while along the remaining portions of their surfaces they are enveloped by a satellite cell sheath, in turn surrounded by a basal lamina and connective tissue. By means of a quantitative study on 108 paired neurons in the spinal ganglia of 3 adult rats, we have found that the overall development of the perikaryal projections does not differ significantly in those surface domains associated only with satellite cells compared with those domains associated with both satellite cells and extracellular matrix. This finding suggests that, in the adult rat, neuron-satellite cell interactions rather than factors in the extracellular matrix play a role in promoting the outgrowth of perikaryal projections from spinal ganglion neurons.