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. 2007 Mar 15;21(6):682–693. doi: 10.1101/gad.1521307

Figure 3.

Figure 3.

Dicer is required for completion of meiotic maturation. (A) Schematic of oocyte maturation and early embryo development. The transition from fully grown GV oocyte to the late one-cell embryo occurs in the absence of significant transcription and relies on translation of maternal mRNA transcripts. The first part of this transition, when an oocyte completes meiosis I and arrests at metaphase of meiosis II is known as meiotic maturation. Zp3-Cre is expressed only in growing oocytes. (B) The maturation stage of Dicer−/− and control oocytes was scored by the presence of a GV (GV oocyte), a polar body (MII oocyte), or neither a GV nor a polar body (MI oocyte). Six-hundred-ninety-four Dicer+/+ and Dicer+/− and 582 Dicer−/− oocytes were analyzed in total. Error bars denote standard error of the mean. (C,D) Spindle morphology in Dicer−/− oocytes matured in vitro to metaphase I (C) or metaphase II (D). Oocytes were fixed in 3.7% paraformaldehyde and stained with a β-tubulin antibody; DNA was counterstained with DAPI or Sytox green. Representative images are shown. Bar, 25 μm. (E) Cortical actin and polar body morphology in mutant oocytes. Oocytes were fixed in 3.7% paraformaldehyde and stained with a β-tubulin antibody; F-actin was labeled with phalloidin-Alexa fluor 635 and DNA was counterstained with DAPI. The arrowheads indicate the position of the first polar body. β-Tubulin is often present inside the polar body in both wild-type and mutant oocytes.