[The ultrastructure and argentophilic properties of the nucleolus organizer and centromeric regions of the chromosomes in early mouse embryogenesis].
The Ag-staining of metaphase chromosomes in one-cell mouse embryos shows that the nucleolus organizer regions (NORs) are Ag-negative, whereas centromeric regions (CRs) are Ag-positive. Starting from 8-16-cell embryos, NORs stained by AgNO3 constantly, CRs remaining argentophobic. On the ultrathin sections of multicell embryos, Ag(+)-NORs differ from the chromosomal arms: they consist of loosely filaments about 6-8 nm in diameter, characterized by a low electron density. On the contrary, at one-cell stage Ag(-)-NORs are not morphologically identified: chromosomal bodies consist of uniform DNP-fibrils about 20 nm in diameter. These data permit to suppose that extended rDNA may form supranucleosomal and nucleosomal DNP-fibrils in the absence of Ag-proteins. The Ag(+)- and Ag(-)-CRs contain 10-20 nm DNP-fibrils mainly, although their density at multicell stages is higher than in one-cell mouse embryos.
Zatsepina
O V
OV
Severova
E L
EL
Dyban
A P
AP
Chentsov
Iu S
IuS
D000818:Animals; D002503:Centromere / Q000648:ultrastructure*; D002871:Chromosome Banding; D002875:Chromosomes / Q000648:ultrastructure*; D002970:Cleavage Stage, Ovum / Q000648:ultrastructure; D004622:Embryo, Mammalian / Q000648:ultrastructure*; D008677:Metaphase; D051379:Mice; D008854:Microscopy, Electron; D009028:Morula / Q000648:ultrastructure; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*
Ul'trastruktura i argentofil'nye svoĭstva iadryshkoobrazuiushchikh i tsentromernykh raĭonov khromosom v rannem émbriogeneze myshi.