Studies on quantitative morphology. XIII. Heterogeneity in the mammary gland of rats

In the rat mammary gland, the distribution of tissues forming this organ is not homogeneous. In order to get representative information about the percentual distribution of lumina, epithelial, adipous and connective tissues it is necessary to take serial sections from the whole organ. This is a very strenuous procedure and is defensible at most in small organs. We demonstrated that, in general, 2-4 histological sections are satisfying all demands when they are taken at distances of about 600-1,000 micron. The percentages of glandular constituents are appropriately ascertained by using a net point system with distances of about 600 micron between single points, provided there is sufficient number of hits. For special purposes, e.g. the recording of drug effects, it is advisable to reduce the distances of step sections to 400-500 micron with net point distances of about 200 micron. Here we found a good compromise complying with both accuracy of results and expenditure of measuring time.