Cytokinesis and cell division during pre-implantation embryonic development occur as an orchestrated spatiotemporal program. Cleavage, compaction, and blastulation in pre-implantation embryos are essential for successful implantation and pregnancy. Their alteration is associated with chromosomal imbalance and loss of developmental competence. In this study, we evaluated the time of cleavage and...

OBJECTIVE To investigate the prevalence, developmental potential, chromosomal constitution and clinical outcome of embryos with direct unequal cleavages (DUC). DESIGN A retrospective observational study. SETTING Academic Institution. PARTICIPANT 21,261 embryos from 3,155 cycles cultured in EmbryoScope®. RESULTS The total incidence of DUCs per embryo occupying the first three cleavages w...

Oocyte maturation and embryonic development are sensitive to DNA damage. Compared with somatic cells or oocytes, little is known about the response to DNA damage in early preimplantation embryos. In this study, we examined DNA damage checkpoints and DNA repair mechanisms in parthenogenetic preimplantation porcine embryos. We found that most of the etoposide-treated embryos showed delay in cleav...

We have measured levels of intracellular free calcium ([Ca2+]i) in albino Xenopus laevis embryos using recombinant aequorin and a photon-counting system. We observed sinusoidal oscillations in [Ca2+]i that had the same frequency as cleavage, with cleavage occurring when [Ca2+]i was lowest. An increase in calcium was seen to precede first cleavage. The cyclic changes in calcium were superimposed...

Both cleavage-stage and blastocyst-stage embryo transfer policieshave advantages and drawbacks.Potential advantages of blastocyst culture and transfer in human IVF include: i. synchronization of the embryo with the female tract leading to increasedimplantation rates; thereby, reducing the need for multipleembryo transfers, ii. assessment of viability of an embryobefore transfer. This can be ach...

  Various recent studies in both human and laboratory animals have indicated an influential role of glucose and phosphate in embryonic development of different strains and species in various media. So this study was initiated to investigate the effects of different concentrations of glucose (G0=0, Gl=0.2, G2=5.5 mM) in the absence (P0) and presence (P1=0.39 mM) of inorganic phosphate, designate...

In developing embryos of some extant spiralian animals, polar lobe formation is one of the symmetry-breaking mechanisms for segregation of maternal cytoplasmic substances to certain blastomeres and not others. Polar lobe formation leads to unique early cleavage morphologies that include trilobed, J-shaped, and five-lobed structures. Fossil embryos similar to modern lobeforming embryos are recog...

The objective of this study was to investigate the frequency and type of chromosome segregation patterns in cleavage stage embryos obtained from male carriers of Robertsonian (ROB) and reciprocal (REC) translocations undergoing preimplantation genetic diagnosis (PGD) at our reproductive center. We used FISH to analyze chromosome segregation in 308 day 3 cleavage stage embryos obtained from 26 p...

BACKGROUND E(epithelial)-cadherin is a vital cell adhesion protein that plays a critical role in morphogenesis. Previous studies of E-cadherin distribution in human embryos have produced equivocal results. METHODS Immunocytochemistry in conjunction with laser scanning confocal microscopy was used to detect E-cadherin in 97 human cleavage stage embryos and 35 blastocysts from normal and abnorm...