Multiplication of nucleolar fibrillar centres and absence of rDNA amplification in mouse oocyte during meiotic prophase I.
During meiotic prophase I the nucleolus of the mouse oocyte assumes a reticulate structure of 'nucleolonema' type. This change coincides with the appearance of several secondary fibrillar centres. The number of these centres at diplotene (97-113), largely exceeds that of nucleolar organizers (4c DNA = 20 NORs). The quantitative analysis of autoradiographs after hybridization in situ with 3H-uridine labelled rRNA, enabled us to demonstrate that the multiplication of the fibrillar centres in mouse oocyte nucleolus during meiotic prophase I is not the result of an amplification of the rDNA. The number of silver grains in pachytene and diplotene nuclei was twice that counted for somatic cell and oogonium nuclei (2c DNA).
D000818:Animals; D002466:Cell Nucleolus / Q000378:metabolism / Q000648:ultrastructure*; D004247:DNA / Q000235:genetics*; D004275:DNA, Ribosomal; D005260:Female; D005796:Genes; D008540:Meiosis; D051379:Mice; D008854:Microscopy, Electron; D009697:Nucleolus Organizer Region / Q000648:ultrastructure; D009865:Oocytes / Q000378:metabolism / Q000648:ultrastructure*; D009866:Oogenesis; D010063:Ovum / Q000648:ultrastructure*; D012335:RNA, Ribosomal / Q000096:biosynthesis; D014158:Transcription, Genetic
D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D004247:DNA