Figure 1.

Aging of dendritic spines in Purkinje cells (DiI diolistic assay).

(A−C) Purkinje cells at various ages. At P7, the Purkinje cells were not mature. (A) A bold primary dendrite extended from the cell body toward the molecular layer, and the primary dendrite branched into 2−3 secondary dendrites. (B) With increasing age, the dendrites branched repeatedly and the Purkinje cells appeared fan-shaped with numerous dendrites in the molecular layer. At P30, the dendrites could reach up to the pia. (C) At P18M, Purkinje cells had aged and had fewer branched dendrites. (D–I): High magnification images of dendritic spines at various ages. (D) At P3, the spines started to sprout with sparse filopodia on dendrites. (E) At P7, the dendritic spines became short, and their number increased. (F) Dense tidy spines were found at P14. (G) At P30, the number of dendritic spines was maximal. (H) At P12M, the dendritic spines started to gradually decrease. (I) At P18M, many dendritic spines were lost. Scale bars: 30 μm in A−C, 5 μm in D−I. P3, P7, P14, P30: Postnatal 3, 7, 14, 30 days; P12M, P18M: postnatal 12, 18 months.