Fig. 5

Number estimation with disector. a Cell number estimation with the disector. Proliferating cells (BrdU positive) are stained with immunohistochemistry in brown. All cells within the counting frame which are present on the reference section (a) but not on the look-up section (a’) are counted (arrow) and vice versa. b Alveolar number estimation with the disector. Bridges (B) are counted in the reference section (b) and look-up section (b’). Note that any bridges in touch with the red exclusion line are not included (red arrow) in the evaluation and those in touch with the green inclusion line are (green arrow)