Figure 2.

The vertical uniform random strategy used in this study. First, a whole brain was scanned to produce 5 mm T1-weighted consecutive MRI sections at an angle of 0° (Sagittal: perpendicular to horizontal axis). Then the same procedure was applied to all angles separately (From angle of 10° to 170°). This resulted in approximately 540 section profiles from one brain (31 sections at a sagittal angle of 0°, 30 sections at an angle of 10°, etc.). Second, a systematic random sampling procedure was carried out in order to obtain sections. A total of 18 series (angles of 0°–170°) was divided into six groups. Thus every group contained three series, for example the 1^st, 2^nd and 3^rd series consisted of angles of 0°, 10° and 20°. Finally, the systematic interval at 30° was determined and random sampling was performed at angles of 0° (Table 3), −10° (Table 2) and −20° (Table 1) in the first, second and third VURS respectively. For example, we chose the 1^st, 7^th, 13^th 19^th and 25^th section profiles from the 20° series, the 2^nd, 8^th, 14^th 20^th and 26^th section profiles from the 50° series, the 3^rd, 9^th, 15^th 21^st and 27^th section profiles from the 80° series, and so on. Procedures for estimating both surface area and volume were applied to 30 section profiles according to stereological principles.