ABSTRACT
The basis for a sound morphometric approach is threefold. This chapter presents this approach, particularly to demonstrate and discuss some useful models and the stereological methods needed to estimate the structural parameters of these models. The main mechanical problem to be solved in lung design is how to keep the alveolar walls with the capillaries well expanded in the air-filled lung, since this is one of the main determinants of gas exchange. The morphometric characterization of the lung cell population is of great importance, particularly when one is considering metabolic properties of the lung, as well as pathological changes. The length density of linear features in space, for example of fibers, is reflected on a random section by the density of their transections on the unit section area. In attempting to characterize the lung's gas exchange properties investigators need to estimate the harmonic mean barrier thickness, and this cannot be obtained by point counting.
