+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Nucleolus organizer regions and nucleoli in preattachment bovine embryos



Nucleolus organizer regions and nucleoli in preattachment bovine embryos



Journal of Reproduction and Fertility 82(1): 87-95



Embryos (1-cell to elongated blastocyst stage) were recovered from super-ovulated heifers at surgery (Days 2-4; oestrus = Day 0), after slaughter (Day 4), or by transcervical flushing (Days 6, 7 and 14). The 175 embryos were cultured for 4, 8, 24 or 48 h, fixed on slides and sequentially stained with Giemsa and silver nitrate. Twenty-three 2-cell to blastocyst-stage embryos were fixed, embedded and examined by transmission electron microscopy. Argentophilic nucleolus organizer regions (Ag-NORs), indicative of transcriptionally active rRNA genes, were observed in embryos in which short- or long-term culture began at or after the late 8-cell stage. The nucleoli of embryonic cells also showed increased affinity for silver from the 8-cell stage onward. Differences in the number of Ag-NORs observed after the 8-cell stage reached statistical significance only when Day-5 and Day-7 embryos cultured for 4 h were compared. Ultrastructurally, the nucleoli were seen to develop from small, dense, fibrillar masses at the 2-cell stage, to ring-shaped structures (signifying a low level of activity) at the 8-cell stage. At the 16-cell stage the nucleoli became reticulated, suggesting an increase in activity, and by the morula and blastocyst stages they were characteristic of fully active nucleoli. It is concluded that a significant transcriptional activity of the rRNA genes in the embryos of cattle begins around the 8-cell stage.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 001644598

Download citation: RISBibTeXText

PMID: 3339599

DOI: 10.1530/jrf.0.0820087


Related references

Nucleolus organizer regions and nucleoli in mammalian embryos. Journal of Reproduction and Fertility. Suppl. 38: 63-71, 1989

Nucleoli and nucleolus organizer regions in early goat embryos. Theriogenology 25(1): 145, 1986

The nucleolus organizer regions of early bovine embryos. Journal of Dairy Science 68(Suppl. 1): 249, 1985

The 3-dimensional organization of the nucleolus and nucleolus-organizer regions of differentiated cells. IV. The structural and functional heterogeneity of the nucleoli in the epithelium of the proximal nephron in the mouse. Tsitologiia 35(10): 3, 1993

Functional morphology of nucleolus organizer regions of chromosomes and nucleoli in human multiple myeloma cell lines. I. Variation of the morphology and silver staining of nucleolus organizer regions of chromosomes in RMPI 8226 and U 266 cell lines with different level of differentiation of during 7 days after cell passage. Tsitologiia 40(6): 536-548, 1998

Nucleolus organizer regions and nucleoli. Human Genetics 63(2): 89-99, 1983

The 3-dimensional organization of the nucleolus and the nucleolus organizer regions in differentiated cells. III. Changes in the nature of the distribution of argentophilic proteins in the nucleoli of mouse hepatocytes with stimulation of the hepatocytes to proliferation. Tsitologiia 34(9): 26-31, 1992

Nucleoli and argyrophil nucleolus organizer regions (AgNORs) of cells of the megakaryocytic line in the rat. Physiological Research 44(3): 193-196, 1995

The 3-dimensional organization of the nucleolus and the nucleolus organizer regions in differentiated cells. II. The reticular, vacuolized and nucleolonemal nucleoli of hepatocytes from the intact mouse liver and of hepatocytes stimulated to proliferation as a result of partial hepatectomy. Tsitologiia 34(9): 17-25, 1992

Expression of chromosomal nucleolus organizer regions and parameters of nucleoli in tissues with different mitotic activity. Chromosome Research 3(Suppl. 1): 92-93, 1995

Number of nucleoli and nucleolar organizer regions per nucleus and nucleolus - prognostic value in canine mammary tumors. Veterinary Pathology 33(5): 527-532, 1996

Satellited chromosomes, nucleolus organizer regions and nucleoli of Brassica campestris L., B. nigra (L.) Koch, and Sinapis arvensis L. Hereditas Landskrona 122(2): 113-118, 1995

Immunocytogenetics localization of transcriptionally active ribosomal rna genes in nucleoli and nucleolus organizer regions by use of human autoantibodies to rna polymerase i. Cytogenetics & Cell Genetics 48(1): 34-42, 1988

Immunocytogenetics: localization of transcriptionally active rRNA genes in nucleoli and nucleolus organizer regions by use of human autoantibodies to RNA polymerase I. Cytogenetics and Cell Genetics 48(1): 35-42, 1988

Immunocytogenetics: localization of transcriptionally active rRNA genes in nucleoli and nucleolus organizer regions by use of human auto antibodies to RNA polymerase I. Cytogenetic and Genome Research 48(1): 35-42, 1988