Engel W, Zenzes M T, Schmid M
Hum Genet. 1977 Aug 31;38(1):57-63. doi: 10.1007/BF00295808.
The Ag-AS method, developed by Goodpasture and Bloom (1975) strains transcriptionally active nucleolus organizer regions (NORs) on the chromosomes and in the interphase nuclei. Metaphases and interphase nuclei of early mouse embryos (unfertilized eggs, pronucleus stages, 2-, 4-, 8-cell stages, and morulae) were subjected to silver-staining. First staining of a single chromosome bearing an NOR was observed at the 2-cell stage. At the 4-cell stage 4--6 chromosomes, and at the 8-cell stage invariably all the 6 chromosomes known to bear NORs, respond positively to silver-staining. These results indicate that during mouse embryogenesis ribosomal RNA genes start to function at the 2-cell stage. The polar body does not respond to silver-staining, which supports the view that the polar body genome remains inactive.
由古德帕斯丘和布卢姆（1975年）开发的银-抗银染色法可对染色体和间期核中转录活跃的核仁组织区（NORs）进行染色。对早期小鼠胚胎（未受精卵、原核期、2细胞期、4细胞期、8细胞期和桑椹胚）的中期相和间期核进行银染。在2细胞期观察到第一条带有NOR的染色体首次染色。在4细胞期，4 - 6条染色体，而在8细胞期，已知带有NOR的全部6条染色体均对银染呈阳性反应。这些结果表明，在小鼠胚胎发生过程中，核糖体RNA基因在2细胞期开始发挥功能。极体对银染无反应，这支持了极体基因组保持无活性的观点。
