title: Ontogeny of the mammalian kidney: expression of aquaporins 1, 2, 3, and 4.
abstract: BACKGROUND
  Determining the expression and functions of aquaporins (AQPs) in the adult kidney has generated important information about the roles of this protein family in the renal regulation of water homeostasis. However, limited information describes the expression of AQPs in fetal kidneys, and most reports on fetal renal AQPs originate from animal studies. Although there are the maturation and regulation of the renal-concentrating mechanism, the ways in which changes in the expression of AQPs contribute to the formation of urine during the perinatal period remain unclear.
  
  
  METHODS
  This review summarizes current knowledge about the spatial and temporal expression patterns of AQP1, AQP2, AQP3, and AQP4 in the fetal and postnatal kidneys in different animal species and in human beings.
  
  
  RESULTS
  AQP1 and AQP2 expression can be detected earlier in gestation in human beings and sheep compared with mice and rats. AQP1 expression is detected earlier in the proximal tubules than the expression of AQP2, AQP3, and AQP4 in the collecting ducts.
  
  
  CONCLUSIONS
  Further studies investigating the regulation of AQPs during kidney development may provide insights into normal water-handling mechanisms and the pathophysiology of fetal kidneys, which may determine new directions for the clinical treatment of kidney diseases.
authors.affiliation: Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: Lu
authors.initials: L
authors.lastname: Xing
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Wen
authors.forename: Jørgen
authors.initials: J
authors.lastname: Frøkiær
authors.forename: Jens Christian
authors.initials: JC
authors.lastname: Djurhuus
authors.forename: Rikke
authors.initials: R
authors.lastname: Nørregaard
mesh_terms: D000818:Animals; D051398:Aquaporin 1 / Q000378:metabolism; D051399:Aquaporin 2 / Q000378:metabolism; D051400:Aquaporin 3 / Q000378:metabolism; D051401:Aquaporin 4 / Q000378:metabolism; D020346:Aquaporins / Q000378:metabolism*; D005333:Fetus / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000196:embryology / Q000378:metabolism*; D051379:Mice; D051381:Rats; D012756:Sheep
chemical_list: D051399:Aquaporin 2; D051401:Aquaporin 4; D020346:Aquaporins; D051398:Aquaporin 1; D051400:Aquaporin 3