Do embryos need oocyte nucleolus?

2014 Fiscal Year Final Research Report

• Project/Area Number: 25660253
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Integrative animal science
• Research Institution: Kobe University
• Principal Investigator: MIYANO TAKASHI 神戸大学, 大学院農学研究科, 教授 (80200195)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 卵母細胞 / 受精卵 / 核小体 / 体外培養 / 顕微操作

Outline of Final Research Achievements

Nucleoli in mammalian oocytes and zygotes, referred to as nucleolus precursor bodies (NPBs), are compact and morphologically different from nucleoli in somatic cells. In this study, nucleoli were removed (enucleolated) from oocytes, parthenogenetically activated pig 1-cell embryos and mouse zygotes by micromanipulation. Nucleoli of oocytes were not necessary for oocyte maturation and fertilization but, in their absence, no nucleoli were formed in zygotes, leading to their developmental failure. Enucleolated 1-cell embryos/zygotes developed to blastocysts and, after transfer of the mouse embryos to recipients, live pups were obtained. Enucleolated zygotes formed new nucleoli after several divisions. These results suggest that oocyte nucleoli are essential for embryonic development, but zygote nucleoli are not. In addition, the enucleolated zygotes formed somatic-type nucleoli during early embryonic development, demonstrating that somatic-type nucleoli do not originate from zygote NPBs.

Free Research Field

統合動物科学