BACKGROUND Selecting the best embryo for transfer, with the highest chance of achieving a vital pregnancy, is a major goal in current in vitro fertilization (IVF) technology. The high rate of embryonic developmental arrest during IVF treatment is one of the limitations in achieving this goal. Chromosomal abnormalities are possibly linked with chromosomal arrest and selection against abnormal fe...

Although vertebrate embryogenesis is typically a continuous and dynamic process, some embryos have evolved mechanisms to developmentally arrest. The embryos of Austrofundulus limnaeus, a killifish that resides in ephemeral ponds, routinely enter diapause II (DII), a reversible developmental arrest promoted by endogenous cues rather than environmental stress. DII, which starts at 24-26 days post...

Tetraploidy can arise from various mitotic or cleavage defects in mammalian cells, and inheritance of multiple centrosomes induces aneuploidy when tetraploid cells continue to cycle. Arrest of the tetraploid cell cycle is therefore potentially a critical cellular control. We report here that primary rat embryo fibroblasts (REF52) and human foreskin fibroblasts become senescent in tetraploid G1 ...

background: successful embryo transfer (et) technique is a fateful step of all efforts to achieve live births from in vitro produced embryos in assisted reproductive techniques or in knockout, transgenic or cloned animal projects. small reproductive tract of mice and limitation of current techniques may not well satisfy the requirements for mass production of genetically modified mice. genetic ...

Embryos from certain strains of mice do not develop into blastocysts when cultured in vitro from the 1- or 2-cell stages but arrest development as 2-cell embryos--a phenomenon referred to as the '2-cell block'. Reciprocal crosses between eggs and sperm of a 'blocking' (CFLP) and 'non-blocking' (F1) strain show that in this combination the genotype of the egg alone determines whether the embryo ...

We have reported elsewhere that offspring from the No. 65 female of Xenopus laevis cleaved normally, but their development was arrested at the onset of gastrulation, like the Ambystoma ova-deficient (o) mutant, irrespective of mating with different wild-type males, and that an acidic, 38 kDa protein present in wild-type eggs was lacking in eggs of the female. In the current study, we first dete...

The effects of exposure to high and very low fluence alpha-particles on the G1 checkpoint were investigated in human diploid fibroblasts irradiated and released from density-inhibited confluent cultures by the use of the cumulative labeling index method. Transient and permanent arrests in G1 occurred in fibroblast populations exposed to mean doses as low as 1 cGy, suggesting that nontraversed b...

Embryos from certain strains of mice do not develop into blastocysts when cultured in vitro from the 1or 2-cell stages but arrest development as 2-cell embryos a phenomenon referred to, as the '2-cell block'. Reciprocal crosses between eggs and sperm of a 'blocking' (CFLP) and 'non-blocking' (Fj) strain show that in this combination the genotype of the egg alone determines whether the embryo 'b...