In histological methods, we are always faced
with two-dimensional sections or their microscopic
images. Stereology, based on mathematics and
statistics, makes it possible to estimate threedimensional
data from two-dimensional profiles
of an object (9). In histology, it helps in measurement
of parameters including number, size, surface
area and volume by two-dimensional tissue
sections (10). As an advantage, it provides the
opportunity of generalizing data to entire structure,
by proper and systematic sampling of the
sections. There is no precise data concerning
structural changes of placenta in PP. In the present
study, the stereological changes of placenta in PP
patients in comparison with healthy controls were
investigated.