title: [Characteristics of the ultrastructural organization of metaphase chromosomes in mouse embryos in the early cleavage stages].
abstract: The structural organization of the mouse metaphase chromosomes in the early embryonic development (I-IV cleavages) was studied using serial ultrathin section. It was shown that in the first cleavage the metaphase chromosomes consist of DNP fibrils 20-25 nm in diameter, which are distributed nonuniformly along the chromosomes. It was suggested that parts of chromosomal arms formed by tightly packing DNP fibrils may correspond to the G-bands revealed by the routine Giemsa staining. In metaphase chromosomes of 8-16-cell embryos DNP fibrils form chromonema--thick threads about 90 nm in diameter. The chromonemata are evenly organized along chromosomal arms. The centromeric heterochromatin always consists of DNP fibrils tightly arranged in a block having no chromonemal level of organization. In all the cells studied chromosomes form structural contacts (associations) by their centromeric heterochromatin regions.
mesh_terms: D000818:Animals; D002842:Chromatids / Q000648:ultrastructure; D002871:Chromosome Banding; D002875:Chromosomes / Q000648:ultrastructure*; D002970:Cleavage Stage, Ovum / Q000648:ultrastructure*; D008677:Metaphase; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008854:Microscopy, Electron
vernacular_title: Osobennosti ul'trastrukturnoĭ organizatsii metafaznykh khromosom zarodysheĭ myshi na rannikh stadiiakh drobleniia.