[The olfactory bulb as a model for experimental studies]

The olfactory bulb represents a model for several research works carried out in our laboratory. Several details concerning structure, cell varieties and connections have been described. Special attention should be given to the ensheathing glia which accompanies olfactory axons, it being responsible for its plasticity and regeneration, as well as intervening in glomerular formation and their specificity. The olfactory system also represents a good model for the study of certain developmental aspects of the nervous system, such as the formation of nerve tracts. The lateral olfactory tract extends into the basal telencephalon and its development is supported by the existence of pre-existing routes and several attractive or repulsive factors. Its development requires complex molecular interactions in combination with several signalling influences. Pax6 is a transcription factor required for brain development. Nasal structures and eyes are absent in the homozygous mutant mice. In this mutant we have described the presence of one particular structure which could be a prospective olfactory bulb. Specific cell markers have been used to demonstrate that this structure shows many structural characteristics of the olfactory bulb. These observations favor the hypothesis of the existence of specific patterns delimiting specific functional domains in absence of their proper afferent fibers.