[Experimental and pathological models that explain the regulation of cellular migration and axon's orientations]

Since Cajal discovery of nerve growth cones and their role in the growth, metabolism and destination of the axon in 1890 numerous studies have corroborated with more sophisticated techniques his original findings and ideas. The use of modified Golgi staining, drawing from the camera lucida in 2 combination with electron microscopy and t retrograde biochemical markers have helped to identify the neuronal sites of synapsis. Dynamic studies of the nerve growth cones using time-lapsed video microscopic images of living neuroblast in t culture or the intact animal have demonstrated their protactil and retractile membranes and exploratory filipodia properties. Interaction between growth cone membrane receptors and different molecules along the migrating axon determine also its final destination. Finally the role that genes play on neuronal migration and in guiding the axons to reach their targets have been identified in patients with Kallmann syndrome, a migrational disorder of olfactory axons and hypothalamic gonadotropic hormone-releasing hormone with absent gene at Xp22.3 locus manifested by anosmia and hypogonadotropic hypogonadism.