Functional features of the nucleolar organizer in developing oocytes of juvenile birds

The genes of rRNA in the nucleolar organizer region (NOR) are inactivated in the oocytes of adult birds despite the functioning of lampbrush chromosomes. The nucleolus is not formed during all stages of the oocyte development. On the other hand, two morphological forms of oocytes differing by the pr...

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Bibliographic Details
Published in:Russian journal of developmental biology 2017-05, Vol.48 (3), p.224-230
Main Authors: Davidian, A. G., Koshel, E. I., Lavrova, O. B., Dyomin, A. G., Galkina, S. A., Saifitdinova, A. F., Gaginskaya, E. R.
Format: Article
Language:English
Subjects:
Animal Anatomy
Antibodies
Biomedical and Life Sciences
Cell Differentiation and Proliferation
Chromosomes
Developmental Biology
Fibrillarin
Fluorescence
Functional anatomy
Gametogenesis
Histology
Hybridization
Immunohistochemistry
Lampbrush
Life Sciences
Morphology
Nucleic acids
Nucleoli
Oocytes
Oogenesis
Ovaries
rRNA
Sex
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Summary:The genes of rRNA in the nucleolar organizer region (NOR) are inactivated in the oocytes of adult birds despite the functioning of lampbrush chromosomes. The nucleolus is not formed during all stages of the oocyte development. On the other hand, two morphological forms of oocytes differing by the presence of nucleolus in the germinal vesicle are described in the ovaries of juvenile birds. The activation and function of the ribosomal genes in avian oogenesis is still vague. In this work, the NOR activation in chicken ( Gallus gallus domesticus ) oocytes is confirmed with the help of fluorescence immunohistochemistry (antibodies against nucleophosmin, fibrillarin, and UBF1) and in situ nucleic acid hybridization (FISH with the probe to ITS1 in pre-rRNA). It is demonstrated that the nucleolus in the oocytes at the lampbrush stage in the chicken ovaries is fragmented after complete inactivation of the ribosome genes: the nucleolar fragments contain fibrillarin but do not contain pre-rRNA molecule. The utility of the ovary 3D reconstruction using serial histological sections for quantification of sex cell population heterogeneity in the ovaries of juvenile birds is demonstrated. The obtained results improve the current insight into the functional NOR state in the oocytes of juvenile female birds and contribute to the concept of diversity in the scenarios of gametogenesis.
ISSN:1062-3604
1608-3326
DOI:10.1134/S1062360417030031