Table 2.

Morphological characteristics of GFP⁺ newly generated granule cells

Morphological characteristic	Four-week-old neurons	Four-month-old neurons	Statistical significance (P)
Area of soma* (µm2)	80.0 (5.6)	138 (14)	0.002
Total dendritic length (µm)	359 (45)	552 (49)	0.01
Number of branch points	4.1 (0.7)	6.8 (0.6)	0.01
Spine density† (µm−1)	0.77 (0.04)	1.19 (0.07)	0.0002

Data are presented as means, with s.e.m. in parentheses. The column on the right shows the statistical signifcance, calculated using a t-test. n = 8 for all characteristics, except spine density for 4-month-old neurons, where n = 5.

^*Maximal cross-sectional area obtained from stereological measurements.

^†Measured over a total dendritic length of 607 µm in newly generated cells at 4 weeks and 638 µm at 4 months after virus injection. The distances between the cell body and the beginning of the measured dendritic segments were similar for the 4-week-old (71 ± 9 µm) and 4-month-old (57 ± 5 µm) neurons (P = 0:2).