[Quantitative age-dependent variations in dendritic spines in the hippocampus (CA1, CA3 and fascia dentata) of the albino mouse].

The dendritic spines of the apical and basal dendrites of pyramidal neurons in CA1 and CA3 and of granule cells in Fascia Dentata were investigated in 19 stages of age, from the 10th to the 190th postnatal day. The results were statistically evaluated. In CA1 and CA3 a first increase in the number of spines (with a maximum at 35 days) is followed by a subsequent decrease up to the 65th day and a further increase up to the 190th day. This developmental pattern is found in the apical dendrites of CA1 and CA3 in all its investigated segments. On the contrary the basal dendrites differ from this pattern. The spines in the Fascia Dentata show a rapid increase up to the 15th postnatal day followed by a slow but constant increase up the end of our study.