It is often assumed that the embryological development of all organs has been clearly established. A glance at the available data on polycystic kidneys, however, is enough to make one realize that, for the kidney at least, this assumption is not true. In order to provide a better basis for understanding the histogenesis of polycystic kidneys, a new study was made by Osathanondh and Potter,1-3 who report their findings in the September issue of the Archives of Pathology. Using microdissection, these investigators were able to visualize the entire system of nephrons and collecting tubules at all stages of development. This report, therefore, presents a clearer description of the developmental changes than had previously been possible with the use of other techniques.
In this study, as in Peter's4 many years ago, renal development is divided into four stages: (1) from 5 to 14 or 15 weeks of fetal life,