The Hagfish Kidney as a Model to Study Renal Physiology and Toxicology

The kidney of the adult hagfish is a comparatively simple organ consisting of large, segmentally arranged glomeruli and two tubules (archinephric ducts, AND) which drain into the cloaca. The biochemical composition, morphology, and function in vitro (permeability of the glomerular barrier to water and proteins) of the glomeruli is similar to that of higher vertebrates. The AND is morphologically characterized by an epithelium with a brush border. The AND reab-sorbs molecules such as glucose or amino acids, expresses enzymes, such as cathepsins or acid phosphatase, but seems to be less active than the corresponding segments (proximal tubules) in higher vertebrates.