title: Development of the pattern of cell renewal in the crypt-villus unit of chimaeric mouse small intestine.
abstract: We have previously shown that the epithelium of each adult intestinal crypt in chimaeric mice is derived from a single progenitor cell. Whether the crypts are monoclonal from the outset-that is, are formed by the proliferation of a single cell-or whether their formation is initiated by several cells was not known. Here we report that many crypts contain cells of both chimaeric genotypes in the neonatal period indicating a polyclonal origin at this stage of morphogenesis. The cellular organization of the early neonatal crypt is therefore different from that of the adult crypt, which includes a zone of 'anchored' stem cells above the crypt base. Within 2 weeks, however, the crypt progenitor cell and its descendants displace all other cells from the crypt and the crypt attains monoclonality. The distribution of enterocytes on chimaeric villi in the neonate shows a mottled pattern of mosaicism which is progressively replaced by coherent sheets of cells from the crypts, and within two weeks the orderly adult clonal pattern is established.
authors.affiliation: Department of Cell Biology, Fraunhofer-Institute, Hannover, FRG.
authors.forename: G H
authors.initials: GH
authors.lastname: Schmidt
authors.forename: D J
authors.initials: DJ
authors.lastname: Winton
authors.forename: B A
authors.initials: BA
authors.lastname: Ponder
mesh_terms: D000818:Animals; D002678:Chimera; D004848:Epithelium / Q000648:ultrastructure; D005838:Genotype; D007421:Intestine, Small / Q000254:growth & development* / Q000648:ultrastructure; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron