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. To delineate the spatiotemporal organization of the first mitotic division typical for normal human embryo development, we systematically analyzed a unique timelapse dataset of 300 IVF embryos that developed into healthy newborns. The zygotic division pattern of these best-quality embryos was compared to their siblings that failed to implant or arrested during cleavage stage. We show that division at the right angle to the juxtaposed pronuclei is preferential and supports faithful zygotic division. Alternative configurations of the first mitosis are associated with reduced clustering of nucleoli and multinucleation at the 2-cell stage, which are more common in women of advanced age. Collectively, these data imply that orientation of the first division predisposes human embryos to genetic (in)stability and may contribute to aneuploidy and age-related infertility.
- MeSH
- aparát dělícího vřeténka * metabolismus MeSH
- buněčné jádro * metabolismus MeSH
- embryo savčí cytologie MeSH
- embryonální vývoj * MeSH
- fertilizace in vitro MeSH
- lidé MeSH
- mitóza * MeSH
- stadium rýhování vajíčka cytologie MeSH
- zygota * metabolismus cytologie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
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. SETTING: University laboratory and imaging center. PATIENTS: A total of 105 women undergoing hormonal stimulation for in vitro fertilization (IVF) donated their spare oocytes for this study. INTERVENTIONS: Transmission electron microscopy (TEM) was used to analyze the fine morphology of 22 dysmorphic IVF oocytes exhibiting different types of cytoplasmic irregularities, namely, refractile bodies; centrally located cytoplasmic granularity (CLCG); smooth endoplasmic reticulum (SER) disc; and vacuoles. A total of 133 immature oocytes were exposed to cytoskeleton-targeting compounds or matured in control conditions, and their morphology was examined using fluorescent and electron microscopy. MAIN OUTCOME MEASURES: The ultrastructural morphology of dysmorphic oocytes was analyzed. Drug-treated oocytes had their maturation efficiency, chromosome-microtubule configurations, and fine intracellular morphology examined. RESULTS: TEM revealed ultrastructural characteristics of common oocyte aberrations and indicated that excessive organelle clustering was the underlying cause of 2 of the studied morphotypes. Inhibition experiments showed that disruption of actin, not microtubules, allows for inordinate aggregation of subcellular structures, resembling the ultrastructural pattern seen in morphologically abnormal oocytes retrieved in IVF cycles. These results imply that actin serves as a regulator of organelle distribution during human oocyte maturation. CONCLUSION: The ultrastructural analogy between dysmorphic oocytes and oocytes, in which actin network integrity was perturbed, suggests that dysfunction of the actin cytoskeleton might be implicated in generating common cytoplasmic aberrations. Knowledge of human oocytes' inner workings and the origin of morphological abnormalities is a step forward to a more objective oocyte quality assessment in IVF practice.
- MeSH
- aktiny * MeSH
- cytoplazma MeSH
- cytoskelet MeSH
- lidé MeSH
- mikrotubuly MeSH
- oocyty * ultrastruktura MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
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. However, two-dimensional micrographs contain only fragmentary information about the spatial organization of the complex oocyte cytoplasm. Here, we employed the Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) to explore human oocyte intracellular morphology in three dimensions (3D). Volume reconstruction of generated image stacks provided an unprecedented view of ooplasmic architecture. Organelle distribution patterns observed in nine donor oocytes, representing three maturational stages, documented structural changes underlying the process by which the egg acquires developmental competence. 3D image segmentation was performed to extract information about distinct organelle populations, and the following quantitative analysis revealed that the mitochondrion occupies ∼ 4.26% of the maturing oocyte cytoplasm. In summary, this proof-of-concept study demonstrates the potential of large volume electron microscopy to study rare samples of delicate female gametes and paves the way for applying the FIB-SEM technique in human oocyte research.
- Publikační typ
- časopisecké články MeSH
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. All PB-displaying oocytes were subjected to polarized light microscopy (PLM) prior to ICSI. When MII spindle was absent in the majority of oocytes, ICSI was postponed and performed after additional spindle imaging. Fertilization, embryo development, and clinical outcome were evaluated with respect to the observed spindle pattern. RESULTS: The visible spindle was absent in 32.64% of PB-displaying oocytes. The late-maturing oocytes extruding PB in vitro were less likely to exhibit a spindle signal than in vivo matured MII oocytes (38.86% vs. 89.84%). When fertilization was postponed, 59.39% of initially spindle-negative oocytes developed detectable MII spindle. Spindled eggs had significantly higher developmental potential, and the presence of the spindle has been identified as an independent measure for predicting the formation of the blastocyst. Embryos derived from spindle-positive oocytes also showed a higher chance to implant and develop to term. Notably, 11 children were conceived by finely timed fertilization of late-maturing oocytes which are normally discarded. CONCLUSIONS: The study confirms the prognostic value of spindle imaging and demonstrates that immature oocytes can be clinically utilized and give rise to live births when the timing of ICSI is adjusted to their developmental stage.
- MeSH
- embryonální vývoj genetika MeSH
- fertilizace in vitro * MeSH
- intracytoplazmatické injekce spermie * MeSH
- lidé MeSH
- metafáze genetika MeSH
- oocyty růst a vývoj ultrastruktura MeSH
- oogeneze genetika MeSH
- polarizační mikroskopie MeSH
- těhotenství MeSH
- Check Tag
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Východiska: Cílem této práce je představit algoritmus separace plazmatických buněk ze vzorků kostní dřeně pacientů s mnohočetným myelomem. Zisk vysoce čistých buněčných populací je základní podmínkou aplikace moderních výzkumných postupů u tohoto onemocnění. Materiál a metody: Vzorky kostní dřeně byly získány od pacientů z Interní hematoonkologické kliniky FN Brno. Kostní dřeň byla nejprve zbavena červené složky (metodou hustotní gradientové centrifugace nebo lyzace), plazmatické buňky byly označeny monoklonální protilátkou proti syndecanu-1 (CD138) a separovány magneticky nebo na buněčném sorteru. Čistota separované populace byla vyhodnocena na průtokovém cytometru, případně morfologicky. Výsledky: Paralelně, magnetickou a fluorescenční separací, bylo zpracováno 28 vzorků kostní dřeně a byla vyhodnocena čistota separovaných frakcí. Na základě statistického hodnocení výsledných čistot jak v celém souboru vzorků, tak ve skupinách podle vstupního zastoupení plazmatických buněk byl navržen algoritmus separace s cut-off hodnotou 5 % plazmatických buněk v mononukleární frakci KD: vzorky s < 5 % plazmatických buněk jsou nadále tříděny na buněčném sorteru, vzorky s ? 5 % plazmatických buněk jsou separovány na magnetickém separátoru. Po ročním vyhodnocení uplatnění tohoto algoritmu na souboru 210 vzorků kostní dřeně se medián čistoty separovaných plazmatických buněk zvedl z 62,4 % (0,4–99,6 %) na 94,0 % (23,9–100 %). Závěr: Zavedení metodiky fluorescenčního třídění výrazně přispělo k celkovému zvýšení úspěšnosti separace plazmatických buněk ze vzorků kostní dřeně, a to především u vzorků s jejich nízkým vstupním zastoupením, kde dosud využívaná metodika magnetické separace není dostatečně účinná. Otevřela se tím také cesta k separaci plazmatických buněk ze vzorků kostní dřeně od jedinců s monoklonální gamapatií nejasného významu, kde je zastoupení plazmatických buněk typicky velmi nízké (desetiny, max. jednotky procent).
Backgrounds: The aim of this paper is to present an algorithm for plasma cell separation from bone marrow samples of multiple myeloma patients. The main prerequisite for applying modern research methods in this disease is gaining pure cell populations. Material and Methods: Bone marrow samples were collected from outpatients or inpatients of the Internal Haematology and Oncology Clinic of the Faculty Hospital Brno, after they had signed an Informed Consent Form. The bone marrow was first depleted of red cells (by density gradient centrifugation or erythrolysis), plasma cells were labelled by monoclonal antibody against syndecan-1 (CD138) and separated either magnetically or by cell sorter. The purity of separated population was evaluated by flow cytometry or, alternatively, morfologically. Results: We processed 28 bone marrow samples, in parallel, by magnetic or fluorescence-based separation, and we evaluated the purity of the separated fractions. Based on a statistical evaluation of resulting purities in the entire sample set as well as the individual groups divided according to the initial plasma cell content, a separation algorithm was proposed with a cut-off value of 5% of plasma cells in mononuclear fraction of bone marrow: samples with less than 5% of plasma cells are henceforth separated on cell sorter, samples with more than 5% are separated magnetically. The effectiveness of this algorithm was evaluated after the first year of its application on a dataset of 210 bone marrow samples: median purity of the separated plasma cells increased from 62.4% (0.4–99.6%) to 94.0% (23.9–100%). Conclusion: The introduction of a fluorescence-based separation markedly increased the effectiveness of plasma cell separation from bone marrow samples, mainly in samples with low plasma cell content where magnetic separation used thus far is not sufficient. This finding also opened a door for plasma cell separation of bone marrow samples from patients with monoclonal gammopathy of undetermined significance, where plasma cell count is typically below or just over one percent.
- Klíčová slova
- magnetická separace, buněčný sorter,
- MeSH
- algoritmy MeSH
- financování organizované MeSH
- imunomagnetická separace MeSH
- kostní dřeň patologie MeSH
- lidé MeSH
- mnohočetný myelom patologie MeSH
- monoklonální gamapatie nejasného významu MeSH
- plazmatické buňky patologie MeSH
- průtoková cytometrie MeSH
- Check Tag
- lidé MeSH
