GDF-9 and BMP-15 direct the follicle symphony.

Understanding the physiology underlying the complex dialog between the oocyte and its surrounding somatic cells within the ovarian follicle has been crucial in defining optimal procedures for the development of clinical approaches in ART for women suffering from infertility and ovarian dysfunction. Recent studies have implicated oocyte-secreted factors like growth differentiation factor 9 (GDF-9) and bone morphogenetic protein 15 (BMP-15), members of the transforming growth factor-beta (TGFβ) superfamily, as potent regulators of folliculogenesis and ovulation. These two factors act as biologically active heterodimers or as homodimers in a synergistic cooperation.

Pre-implantation developmental potential from in vivo and in vitro matured mouse oocytes: a cytoskeletal perspective on oocyte quality.

Purpose: In the present study, fertilization and developmental potential of mouse oocytes matured in different conditions were tested. The efficiency of in vitro fertilization (IVF), pre-implantation development and some important aspects of cytokinesis during early cleavages are discussed.

Methods: In vivo matured (IVO), in vitro matured (IVM) and roscovitine-treated (IVM-Rosco) mouse oocytes were subjected to IVF under identical conditions.

Genetic strain variations in the metaphase-II phenotype of mouse oocytes matured in vivo or in vitro.

The interplay between genetic and epigenetic factors plays a central role in mammalian embryo production strategies that superimpose ex vivo or in vivo manipulations upon strain background characteristics. In this study, we examined the relationship between genetic background and the phenotypic properties of mouse metaphase-II (M-II) oocytes that were matured under in vivo (IVO) or in vitro conditions, either in a basal (IVM) or a supplemented (IVM + ) medium. Differences existed amongst inbred (C57BL/6), outbred (CF-1, Black Swiss, NU/NU) and hybrid lines (B6D2F1) induced to superovulate with regard to cytoplasmic microtubule organizing center (MTOC) number but not spindle size or shape, except for larger and asymmetrical spindles in Black Swiss oocytes.

Cell polarity during folliculogenesis and oogenesis.

Polarity is an important aspect of oogenesis and early development for many animal groups, but only recently it has become relevant to the study of mammals. Mammalian oocyte development occurs through tight coordination and interaction between all ovarian structures. In fact, bi-directional communication between the oocyte and its companion granulosa cells (GC) in the ovarian follicle seems essential for GC proliferation, differentiation, and production of a functional female gamete.

Meiotic spindle morphogenesis in in vivo and in vitro matured mouse oocytes: insights into the relationship between nuclear and cytoplasmic quality.

Background: This work addresses the hypothesis that events occurring within the follicle soon after the LH surge are essential for coordinating morphogenesis of the spindle and cytoplasm in mouse oocytes matured in vivo (IVO); we further tested whether in vitro maturation (IVM) fails to support these events.

Methods: Oocytes collected at 1, 2, 3, 4 and 5 h post-hCG or after IVM were analyzed for chromatin, nuclear lamina, microtubules (MTs) and centrosomal proteins by conventional fluorescence and confocal microscopy. In addition, these parameters were monitored in oocytes maintained in 50 microM roscovitine, followed by IVM, or in oocytes retrieved at 1.

Distinctions in meiotic spindle structure and assembly during in vitro and in vivo maturation of mouse oocytes.

To better understand the differences in cytoskeletal organization between in vivo (IVO) and in vitro (IVM) matured oocytes, we analyzed remodeling of the centrosome-microtubule complex in IVO and IVM mouse oocytes. Fluorescence imaging revealed dramatic differences in meiotic spindle assembly and organization between these two populations. Metaphase spindles at both meiosis I (M-I) and meiosis II (M-II) in IVO oocytes were compact, displayed focused spindle poles with distinct gamma-tubulin foci, and were composed of acetylated microtubules.

Origins and manifestations of oocyte maturation competencies.

Mammalian oocytes acquire a series of competencies during follicular development that play critical roles at fertilization and subsequent stages of preimplantation embryonic development. These competencies involve remodelling of chromatin and the cytoskeleton in the oocyte at critical stages of folliculogenesis when gametes and somatic cells communicate by paracrine and junctional mechanisms. While the detailed steps involved in bi-directional signalling between oocytes and granulosa cells remain unknown, studies from mice bearing targeted deletions in essential 'communication' genes reveal selective disturbances in oocyte maturation competencies that compromise the oocyte's developmental potential.