Quantification of Developmental Branching Morphogenesis

One of the great challenges in becoming a large, multicellular organism is that the concomitant decrease in the surface area?to?volume ratio brings with it problems of exchanging oxygen, nutrients, and waste. This is particularly the case in the kidney because the organ is required to facilitate the exchange of blood-borne wastes and to remove them from the body. One of the most successful evolutionary solutions to this problem is the development of branching morphogenesis as a mechanism by which to establish the basic framework for organ development. This process establishes a collection of interconnecting ducts or tubes with ready access to internal tissues that increases the effective surface area-to-volume ratio of a given piece of tissue. In the lung this network forms the airways; in the breast, the milk-conducting ducts; and in the kidney it establishes the collecting ducts that drain urine from the nephrons to the ureter and, eventually, the bladder.