<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" article-type="research-article" dtd-version="1.2" xml:lang="ru"><front><journal-meta><journal-id journal-id-type="publisher-id">Russian Journal of Developmental Biology</journal-id><journal-title-group><journal-title>Russian Journal of Developmental Biology</journal-title></journal-title-group><issn publication-format="print">0475-1450</issn><issn publication-format="electronic">3034-6266</issn><publisher><publisher-name>Russian Academy of Science</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.31857/S0475145023010032</article-id><title-group><article-title>Nucleolus Organizer Region Functioning in Chicken Growing Oocytes: A Revision of the Existing Views</article-title><trans-title-group xml:lang="ru"><trans-title>Функционирование ядрышкового организатора в растущих ооцитах кур: ревизия существующих представлений</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><contrib-id contrib-id-type="orcid"></contrib-id><name-alternatives><name xml:lang="en"><surname>Davidian</surname><given-names>A. G.</given-names></name><name xml:lang="ru"><surname>Давидьян</surname><given-names>А. Г. </given-names></name></name-alternatives><email>a.davidian@spbu.ru</email><xref ref-type="aff" rid="aff-1"></xref><xref ref-type="aff" rid="aff-2"></xref></contrib></contrib-group><aff-alternatives id="aff-1"><aff><institution xml:lang="ru">Санкт-Петербургский государственный университет</institution><institution xml:lang="en">St Petersburg University</institution></aff></aff-alternatives><aff-alternatives id="aff-2"><aff><institution xml:lang="ru"></institution><institution xml:lang="en"></institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2023-01-01" publication-format="electronic"><day>01</day><month>01</month><year>2023</year></pub-date><volume>54</volume><issue>1</issue><fpage>18</fpage><lpage>26</lpage><abstract xml:lang="en"><p>It is believed that the nucleolus organizer region (NOR) in the ovary of adult birds is inactivated at all stages of oocyte growth. However, in the ovary of juvenile chicken (Gallus g. domesticus) one or two nucleoli were observed in 50% of early diplotene oocytes. These nucleoli were functioning up to the lampbrush stage. It was assumed that diplotene oocytes with inactivated NOR are stored as a pool for development in the ovary of adult hens. Such a contradiction in the NOR functional activity in the oocytes of juvenile and adult hens required special studies. Here we represent new results of a comparative study of the nucleoli in oocytes of juvenile and adult hens. We show for the first time that in the oocytes of laying hens the nucleolus appears at the early diplotene stage and the pre-rRNA synthesis continues up to the lampbrush stage. At the lampbrush stage, the NOR is getting inactivated. The nucleolus disintegrates into large fragments containing both pre-rRNA and fibrillarin. Then these larger fragments break down into small granules that do not contain pre-rRNA but contain fibrillarin. The results resolve the above contradiction and demonstrate a similar pattern of NOR functioning in oocytes of adult and juvenile birds.</p></abstract><trans-abstract xml:lang="ru"><p>В современной литературе утвердилось представление о том, что в яичнике взрослых самок птиц ядрышковый организатор (ЯОР) инактивирован на всех стадиях роста ооцита. Однако на примере яичника цыплят Gallus g. domesticus, в половине ооцитов стадии ранней диплотены обнаруживали одно или два ядрышка, которые функционировали вплоть до стадии развитых ламповых щеток. Предполагалось, что диплотенные ооциты с инактивированным ЯОР у цыпленка сохраняются как резерв для развития в яичнике взрослой самки. Такое несоответствие в функциональной активности ЯОР в ооцитах цыпленка и взрослой самки требовало специальных исследований. Здесь мы приводим новые результаты сравнительного анализа ядрышка в ооцитах у цыплят и у половозрелых кур. Мы впервые показываем, что в ооцитах взрослых кур, как и у цыплят, ядрышко появляется на стадии ранней диплотены и синтез пре-рРНК в нем продолжается до стадии ламповых щеток. На стадии ламповых щеток ЯОР инактивируется: ядрышко распадается на крупные фрагменты, содержащие как пре-рРНК, так и фибрилларин, а затем на мелкие гранулы, которые не содержат пре-рРНК, но содержат фибрилларин. Результаты устраняют указанное выше противоречие и демонстрируют сходный алгоритм функционирования ЯОР в ооцитах у половозрелых и неполовозрелых самок птиц.</p></trans-abstract><kwd-group xml:lang="en"><kwd>курица ооциты диплотена гены рРНК ядрышковый организатор (ЯОР) ядрышко</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>курица ооциты диплотена гены рРНК ядрышковый организатор (ЯОР) ядрышко</kwd></kwd-group><funding-group xml:lang="ru"><funding-statement>Настоящее исследование посвящается 100-летию создания профессором П.П. Ивановым кабинета эмбриологии – предшественника кафедры эмбриологии Санкт-Петербургского государственного университета. Авторы благодарны Александру Демину и ООО “Бигль” за разработку и синтез праймеров. В работе использовано оборудование Научного парка СПбГУ (ЦКП “Хромас”).</funding-statement></funding-group><funding-group xml:lang="en"><funding-statement>Настоящее исследование посвящается 100-летию создания профессором П.П. Ивановым кабинета эмбриологии – предшественника кафедры эмбриологии Санкт-Петербургского государственного университета. Авторы благодарны Александру Демину и ООО “Бигль” за разработку и синтез праймеров. В работе использовано оборудование Научного парка СПбГУ (ЦКП “Хромас”).</funding-statement></funding-group></article-meta></front><body></body><back><ref-list><ref id="B1"><label>B1</label><citation-alternatives><mixed-citation xml:lang="ru">Боголюбов Д.С. Безмембранные органеллы эукариотической клетки: основные понятия и принципы формирования // Цитология. 2019. 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