title: The ultrastructure of the thin limbs of Henle in Kidneys of the desert heteromyid (Perognathus penicillatus).
abstract: The thin limbs of both long- and short-looped nephrons in Perognathus kidneys were studied with transmission and scanning electron microscopy. The superficial nephrons have a short thin limb located in the vascular bundles of the outer medulla and are characterized by a simple, low-lying epithelium (0.4 +/- 0.1 mu thickness). In contrast, the first descending part of the thin limb of the majority of midcortical and juxtamedullary nephrons has a relatively thick epithelium (1.7 +/- 0.6 mu in thickness) with marked lateral and basal interdigitation and a dense surface covering of microvilli. The remaining part of the long descending thin limb is relatively simple with a low-lying epithelium (0.6 +/- 0.1 mu in thickness), decorated on its surface by sparse microplicae. The bend of the loop and the ascending limb are covered by a very simple low-lying epithelium (0.6 +/- 0.2 mu in thickness) with relatively little surface modification. The extreme urine-concentrating ability of Perognathus does not appear to be due to the development of a unique thin loop epithelium but rather to the extensive length of the inner and outer medulla.
mesh_terms: D000818:Animals; D002923:Cilia / Q000648:ultrastructure; D004848:Epithelium / Q000648:ultrastructure; D007684:Kidney Tubules / Q000648:ultrastructure*; D008138:Loop of Henle / Q000648:ultrastructure*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008871:Microvilli / Q000648:ultrastructure; D012377:Rodentia / Q000033:anatomy & histology*; D013045:Species Specificity