In primary or physiological ageing, the brain undergoes a 10% weight reduction. This datum was confirmed in vivo by radiological investigation and post mortem by morphological research (Grandi and Coll. 1990, 1990, 1991, 1991), that underscores the same reduction in the medulla oblongata and in the cerebellum. Morphological and cytohistological aspects of primary ageing have been considered for the inferior olivary nucleus and for the dentate nucleus in 41 male subjects, 32 belonging to the decades 7th, 8th, 9th, and 9 to the decades from the 3rd to the 6th. From the two latter structures, separated along standard cut surfaces, serial histological slices were carried out, and histochemical reactions were accomplished, together with immunohistochemistry, for synaptophysin, NF-2F11, NSE, S-100, GFAP, chromogranin. As the weight progressively decreased from the 7th to the 9th decade, it was noted neuronal loss, both in the inferior olivary nucleus, and in the dentate nucleus. Furthermore, the loss appeared to be followed by substitutive astroglial proliferation. Immunocytochemical reaction for synaptophysin revealed peculiar aspects. A consistently regular result of such method concerned the two nuclei studied, in primary ageing, thus allowing the interpretation of the perfect structure of synaptic vesicles as an indirect argument for neuronal plasticity.