Female-age-dependent changes in the lipid fingerprint of the mammalian oocytes.

Study Question: Can oocyte functionality be assessed by observing changes in their intracytoplasmic lipid droplets (LDs) profiles?

Summary Answer: Lipid profile changes can reliably be detected in human oocytes; lipid changes are linked with maternal age and impaired developmental competence in a mouse model.

What Is Known Already: In all cellular components, lipid damage is the earliest manifestation of oxidative stress (OS), which leads to a cascade of negative consequences for organelles and DNA. Lipid damage is marked by the accumulation of LDs.

Zygotic spindle orientation defines cleavage pattern and nuclear status of human embryos.

The first embryonic division represents a starting point for the development of a new individual. In many species, tight control over the first embryonic division ensures its accuracy. However, the first division in humans is often erroneous and can impair embryo development.

The ultrastructural nature of human oocytes' cytoplasmic abnormalities and the role of cytoskeleton dysfunction.

Objective: To investigate the structural bases of human oocytes' cytoplasmic abnormalities and the causative mechanism of their emergence. Knowledge of an abnormal oocyte's intracellular organization is vital to establishing reliable criteria for clinical evaluation of oocyte morphology.

Design: Laboratory-based study on experimental material provided by a private assisted reproduction clinic.

Actin-driven chromosome clustering facilitates fast and complete chromosome capture in mammalian oocytes.

Accurate chromosome segregation during meiosis is crucial for reproduction. Human and porcine oocytes transiently cluster their chromosomes before the onset of spindle assembly and subsequent chromosome segregation. The mechanism and function of chromosome clustering are unknown.

MAIA, Fc receptor-like 3, supersedes JUNO as IZUMO1 receptor during human fertilization.

Gamete fusion is a critical event of mammalian fertilization. A random one-bead one-compound combinatorial peptide library represented synthetic human egg mimics and identified a previously unidentified ligand as Fc receptor-like 3, named MAIA after the mythological goddess intertwined with JUNO. This immunoglobulin super family receptor was expressed on human and played a major role during sperm-egg adhesion and fusion.

High-Resolution 3D Reconstruction of Human Oocytes Using Focused Ion Beam Scanning Electron Microscopy.

The egg plays a pivotal role in the reproduction of our species. Nevertheless, its fundamental biology remains elusive. Transmission electron microscopy is traditionally used to inspect the ultrastructure of female gametes.

Xeno- and feeder-free derivation of two sex-discordant sibling lines of human embryonic stem cells.

Human embryonic stem cells (hESCs) represent a virtually unlimited source of cells suitable for a variety of biomedical applications. However, a diminishing allogeneic background and undefined culture conditions are essential for developing robust and replicable protocols for differentiation experiments, disease modeling, and drug testing. Therefore, here we report the generation of the two sex-discordant sibling hESC lines, MUNIe008-A and MUNIe009-A, using the mechanical biopsy of vitrified-thawed embryos under xeno- and feeder-free conditions.

Live birth achieved despite the absence of ejaculated spermatozoa and mature oocytes retrieved: a case report.

The most common reason for in vitro fertilization (IVF) cycle cancelation is a lack of quality gametes available for intracytoplasmic sperm injection (ICSI). Here we present the successful fertility treatment of the couple affected by obstructive azoospermia combined with suboptimal response to controlled ovarian stimulation. Since the conventional approach appeared ineffective to overcome both partners' specific problems, the targeted interventions, namely, (1) pharmacological enhancement of sperm motility and (2) polarized light microscopy (PLM)-guided optimization of ICSI time, were applied to rescue the cycle with only immature oocytes and immotile testicular sperm retrieved.

Perfect date-the review of current research into molecular bases of mammalian fertilization.

Fertilization is a multistep process during which two terminally differentiated haploid cells, an egg and a sperm, combine to produce a totipotent diploid zygote. In the early 1950s, it became possible to fertilize mammalian eggs in vitro and study the sequence of cellular and molecular events leading to embryo development. Despite all the achievements of assisted reproduction in the last four decades, remarkably little is known about the molecular aspects of human conception.

Human Egg Maturity Assessment and Its Clinical Application.

The optimal timing of intracytoplasmic sperm injection (ICSI) is of a serious concern for fertility programs because untimely sperm entry diminishes the egg's developmental competence. Presence of the first polar body (PB) together with the meiotic spindle indicates completion of the oocyte maturation and the egg's readiness for fertilization. In clinical practice, it is customary to assume that all oocytes displaying a PB are mature metaphase (MII) oocytes.

Egg maturity assessment prior to ICSI prevents premature fertilization of late-maturing oocytes.

Propose: The presence of metaphase II (MII) spindle together with the polar body (PB) indicates completion of oocyte maturation. This study was designed to explore if spindle imaging can be used to optimize timing of intracytoplasmic sperm injection (ICSI).

Methods: The study involved 916 oocytes from 234 conventionally stimulated ICSI cycles with an unexpectedly poor ovarian response.

Presence of growth/differentiation factor-15 cytokine in human follicular fluid, granulosa cells, and oocytes.

Purpose: The purpose of the study was to determine whether the GDF-15 is present in follicular fluid; to evaluate if there is a relation between follicular and serum levels of GDF-15 and fertility status of study subjects; and to test whether granulosa cells, oocytes, or both produce GDF-15.

Methods: This study used follicular fluid (FF, serum, and oocytes obtained under informed consent from women undergoing oocyte retrieval for in vitro fertilization. It also used ovaries from deceased preterm newborns.

Soluble Cripto-1 Induces Accumulation of Supernumerary Centrosomes and Formation of Aberrant Mitoses in Human Embryonic Stem Cells.

Chromosomal instability evoked by abnormalities in centrosome numbers has been traditionally considered as a hallmark of aberrant, typically cancerous or senescent cells. We have reported previously that pristine human embryonic stem cells (hESC) suffer from high frequency of supernumerary centrosomes and hence may be prone to undergo abnormal mitotic divisions. We have also unraveled that this phenomenon of multicentrosomal mitoses vanishes with prolonged time in culture and with initiation of differentiation, and it is strongly affected by the culture substratum.

Sister kinetochore splitting and precocious disintegration of bivalents could explain the maternal age effect.

Aneuploidy in human eggs is the leading cause of pregnancy loss and Down's syndrome. Aneuploid eggs result from chromosome segregation errors when an egg develops from a progenitor cell, called an oocyte. The mechanisms that lead to an increase in aneuploidy with advanced maternal age are largely unclear.

Human oocytes. Error-prone chromosome-mediated spindle assembly favors chromosome segregation defects in human oocytes.

Aneuploidy in human eggs is the leading cause of pregnancy loss and several genetic disorders such as Down syndrome. Most aneuploidy results from chromosome segregation errors during the meiotic divisions of an oocyte, the egg's progenitor cell. The basis for particularly error-prone chromosome segregation in human oocytes is not known.

Vesicles modulate an actin network for asymmetric spindle positioning.

Actin networks drive many essential cellular processes, including cell migration, cytokinesis and tissue morphogenesis. However, how cells organize and regulate dynamic actin networks that consist of long, unbranched actin filaments is only poorly understood. This study in mouse oocytes reveals that cells can use vesicles as adaptable, motorized network nodes to regulate the dynamics and density of intracellular actin networks.

Cell cycle regulation in human embryonic stem cells: links to adaptation to cell culture.

Cell cycle represents not only a tightly orchestrated mechanism of cell replication and cell division but it also plays an important role in regulation of cell fate decision. Particularly in the context of pluripotent stem cells or multipotent progenitor cells, regulation of cell fate decision is of paramount importance. It has been shown that human embryonic stem cells (hESCs) show unique cell cycle characteristics, such as short doubling time due to abbreviated G1 phase; these properties change with the onset of differentiation.

MicroRNAs regulate p21(Waf1/Cip1) protein expression and the DNA damage response in human embryonic stem cells.

Studies of human embryonic stem cells (hESCs) commonly describe the nonfunctional p53-p21 axis of the G1/S checkpoint pathway with subsequent relevance for cell cycle regulation and the DNA damage response (DDR). Importantly, p21 mRNA is clearly present and upregulated after the DDR in hESCs, but p21 protein is not detectable. In this article, we provide evidence that expression of p21 protein is directly regulated by the microRNA (miRNA) pathway under standard culture conditions and after DNA damage.

Human embryonic stem cells suffer from centrosomal amplification.

Propagation of human embryonic stem cells (hESCs) in culture tends to alter karyotype, potentially limiting the prospective use of these cells in patients. The chromosomal instability of some malignancies is considered to be driven, at least in part, by centrosomal overamplification, perturbing balanced chromosome segregation. Here, we report, for the first time, that very high percentage of cultured hESCs has supernumerary centrosomes during mitosis.

Human embryonic stem cells are capable of executing G1/S checkpoint activation.

Embryonic stem cells progress very rapidly through the cell cycle, allowing limited time for cell cycle regulatory circuits that typically function in somatic cells. Mechanisms that inhibit cell cycle progression upon DNA damage are of particular importance, as their malfunction may contribute to the genetic instability observed in human embryonic stem cells (hESCs). In this study, we exposed undifferentiated hESCs to DNA-damaging ultraviolet radiation-C range (UVC) light and examined their progression through the G1/S transition.