Accuracy in chromosome segregation depends on the assembly of a bipolar spindle. Unlike mitotic spindles, which have roughly equal amounts of kinetochore microtubules (kMTs) and nonkinetochore microtubules (non-kMTs), vertebrate meiotic spindles are predominantly comprised of non-kMTs, a large subset of which forms an antiparallel "barrel" array at the spindle equator. Though kMTs are needed to...

Background: The meiotic spindle plays an important role in the oocyte during chromosome alignment and separation at meiosis. The zona pellucid (ZP) is a dynamic matrix composed of filaments with the properties that might reflect the history of oocyte cytoplasmic maturation. Since, spindle and ZP in living oocytes are highly birefringent, their structures can be viewed noninvasively by using a P...

Background: It is a common practice to rest vitrified-warmed matured oocytes for 1-3 hours, as a treatment to recover spindle and cytoskeleton, before commencing a further treatment. Vitrified-warmed matured oocytes, however, are very sensitive and may resume meiosis spontaneously during this recommended rest time. Therefore, the aim of this study was to assess spindle and chromosome status as ...

The objective of this meta-analysis was to investigate the influence of meiotic spindle visualization in human oocytes on intracytoplasmic sperm injection (ICSI) outcomes. Search strategies included on-line surveys of databases (MEDLINE, EMBASE, Science Citation Index, Cochrane Controlled Trials Register and Ovid). The fixed effect was used for odds ratio. Ten trials fulfilled the inclusion cri...

In both vertebrates and invertebrates, meiotic divisions in oocytes are typically asymmetric, resulting in the formation of a large oocyte and small polar bodies. The size difference between the daughter cells is usually a consequence of asymmetric positioning of the spindle before cytokinesis. Spindle movements are often related to interactions between the cell cortex and the spindle asters [1...

Oocyte meiotic spindles are associated with spindle-enriched mRNAs, phosphorylated ribosome protein S6, and phosphorylated variants of the key translational regulator, eukaryotic translation initiation factor 4E-binding protein 1 (eIF4E-BP1), consistent with translational control of localized mRNAs by eIF4E-BP1 in facilitating spindle formation and stability. Using specific kinase inhibitors, w...

Formin-2 (Fmn2) nucleates actin filaments required for spindle migration during the metaphase of meiosis I in mouse oocytes. While recent studies showed that Fmn2 is involved in the formation of a dynamic actin meshwork on meiotic spindle and the migration of chromosomes, the precise location and the mechanism of action of Fmn2 in the mouse oocyte is not known. In this work, we show that Fmn2 i...

During the first meiotic cell division of the Xenopus oocyte, a transient microtubule network appears at the basal part of the disintegrating nucleus. In order to know if this structure plays a role in the formation of the first meiotic spindle, we have studied the actions of Ca2+ ions and taxol during the whole maturation process. We now report that when the free cytosolic Ca2+ concentration i...

Gametogenesis in animal oocytes reduces the diploid genome content of germline precursors to a haploid state in gametes by discarding ¾ of the duplicated chromosomes through a sequence of two meiotic cell divisions called meiosis I and II. The assembly of the microtubule-based spindle structure that mediates this reduction in genome content remains poorly understood compared to our knowledge of...

In a wide range of eukaryotes, chromosome segregation occurs through anaphase A, in which chromosomes move toward stationary spindle poles, anaphase B, in which chromosomes move at the same velocity as outwardly moving spindle poles, or both. In contrast, Caenorhabditis elegans female meiotic spindles initially shorten in the pole-to-pole axis such that spindle poles contact the outer kinetocho...