Fig. 4

Example of volume and surface area estimation with stereological probes. a Lung volume estimation by Cavalieri method: a point grid with a known area per point is superimposed over mouse lung sections. The number of points multiplied by the area per point and the slice thickness will result in the total lung volume. b Volume estimation of parenchymal (P) and non-parenchymal (NP) lung volume by point counts. Note that a four-fold coarse point grid was included for the counting of parenchymal points. c Volume estimation of alveolar septa (S) and airspace (A) by point counts and estimation of alveolar surface area with line probe intersections (I). d Quantification of mucus per length of basement membrane on AB/PAS mucus positive section (purple). The volume of mucus (M) and epithelium (E + M) is estimated with point counts and the surface area of the basement membrane with the line probe intersections (I). A fifty-fold coarse point grid was included for the counting of lung tissue points (L)