The first edition of this book was well received by updated. The two of us have made further collab orative efforts to present a better understanding of medical students, graduate students, and clinicians interested in furthering their understanding of basic the function of the kidney in conjunction with the principles of renal physiology. Most of the reviews most recent anatomical findings. of the first edition and comments from the various The second edition consists of 13 Chapters and 3 instructors who used the book were very positive Appendices. As in the first edition, the anatomical and complimentary with regard to the presentation description of the kidney is incorporated into the of the physiological information and the use of the various chapters dealing with kidney functions. Most system analysis approach to describe renal function. of the anatomical information was written by Wil These positive and encouraging comments over the helm Kriz. The physiological information was writ past nine years, since the publication of the first ten by Esmail Koushanpour, except for Chapter 12 edition, gave us the impetus to consider the prepa which was jointly written. Chapters 1 through 3 were ration of a second edition."

Glomerular flltration represents one of the basic mechanisms in the function of an organism. Our understanding of this process is still quite fragmentary. Regulation of blood flow and pressure, together with regulation of the ultraflltration coefficient (which is an attribute of the flltration barrier), are the two fundamental mechanisms accounting for maintenance and adaptability of glomerular flltration. Regulation of glomerular blood flow is generally considered to result from an interplay between afferent and efferent glomerular arterioles, and much progress has been made recently in understanding this interplay (Navar et al. 1996). The present study provides a detailed structural description of the glomerular vascular pole of rat. The results of this study appear to be relevant for several open questions of glomerular function. First, the interaction between afferent and efferent arterioles in regulating glomerular blood is generally understood to occur between the preglomerular and the postglomerular portions of these vessels. As shown in the present study, the structural elaborations of these arterioles and the spatial relationships between them within the glomerular hilum strongly suggest an interplay also at this site. Moreover, the current understanding of glomerular blood flow regulation by tuning the interplay between afferent and efferent arterioles is exclusively based on signals whose regulatory loops are established in follow-up events outside the glomerulus (tubuloglomerular balance, tubuloglomerular feedback).