title: Evidence of repetitive patterns of chromatin distribution in cell nuclei of rat liver.
abstract: Samples of rat livers were fixed in glutaraldehyde, contrasted en bloc with phosphotungstic acid, embedded in an epoxy resin and serially sectioned. The study of three-dimensional models of 20 complete nuclei shows that all of them share some general features: they have more than one nucleolus (2-4), an irregular layer of compact chromatin adjacent to the nuclear membrane and well-delimited clumps of chromatin both in the nuclear sap and surrounding the nucleoli. A space of 8 sections containing the central nucleolus and a lateral one was studied in detail. In this space, 8 clumps of compact chromatin were found in 17 nuclei and 9 clumps in the other 3 nuclei. No other number of clumps was found in those zones. In all the nuclei studied the compact chromatin surrounding the central nucleolus contacts the nuclear envelope. This contact takes place in a region almost diametrically opposed to the lateral nucleolus in 13 nuclei. In 7 nuclei, these structures were at angles between 50 and 125 degrees. These results support the existence of nonrandom repetitive patterns of chromatin distribution in liver cells.
authors.affiliation: Departamento de Biología, Facultad de Ciencias, U.N.A.M. Ciudad de México.
authors.forename: C
authors.initials: C
authors.lastname: Esquivel
authors.forename: G H
authors.initials: GH
authors.lastname: Vázquez-Nin
authors.forename: O
authors.initials: O
authors.lastname: Echeverría
mesh_terms: D000818:Animals; D002466:Cell Nucleolus / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure*; D002843:Chromatin / Q000648:ultrastructure*; D008099:Liver / Q000166:cytology*; D008961:Models, Structural; D051381:Rats
chemical_list: D002843:Chromatin