title: Lack of cilia and differentiation defects in the liver of human foetuses with the Meckel syndrome.
abstract: OBJECTIVE
  Meckel syndrome is an autosomal-recessive disease characterized by a combination of renal cysts, anomalies of the central nervous system, polydactyly and ductal plate malformations (DPM), which are hepatic anomalies consisting of excessive and abnormal foetal biliary structures. Among the genomic loci associated with Meckel syndrome, mutations in four genes were recently identified. These genes code for proteins associated with primary cilia and are possibly involved in cell differentiation. The aim of the present work was to investigate the formation of the primary cilia and the differentiation of the hepatic cells in foetuses with Meckel syndrome.
  
  
  METHODS
  Sections of livers from human foetuses with Meckel syndrome were analysed by immunofluorescence, immunohistochemistry and electron microscopy.
  
  
  RESULTS
  The primary cilia of the biliary cells were absent in some Meckel foetuses, but were present in others. In addition, defects in hepatic differentiation were observed in Meckel livers, as evidenced by the presence of hybrid cells co-expressing hepatocytic and biliary markers.
  
  
  CONCLUSIONS
  Defects in cilia formation occur in some Meckel livers, and most cases show DPM associated with abnormal hepatic cell differentiation. Because differentiation precedes the formation of the cilia during liver development, we propose that defective differentiation may constitute the initial defect in the liver of Meckel syndrome foetuses.
authors.affiliation: Université catholique de Louvain, de Duve Institute, Brussels, Belgium.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Clotman
authors.forename: Louis
authors.initials: L
authors.lastname: Libbrecht
authors.forename: Murray C
authors.initials: MC
authors.lastname: Killingsworth
authors.forename: Christine C K
authors.initials: CC
authors.lastname: Loo
authors.forename: Tania
authors.initials: T
authors.lastname: Roskams
authors.forename: Frédéric P
authors.initials: FP
authors.lastname: Lemaigre
mesh_terms: D000015:Abnormalities, Multiple / Q000473:pathology*; D001653:Bile Ducts, Intrahepatic / Q000002:abnormalities* / Q000473:pathology; D002454:Cell Differentiation / Q000502:physiology*; D002923:Cilia / Q000473:pathology*; D005333:Fetus; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D008099:Liver / Q000196:embryology* / Q000473:pathology; D013577:Syndrome