BACKGROUND There are conflicting results on whether the rate of blastocyst development before freezing influences the outcome of frozen-thawed blastocyst transfers. METHODS We conducted a systematic review and meta-analysis of controlled studies to compare pregnancy outcomes following transfer of thawed blastocysts that were frozen either on Day 5 or Day 6 following fertilization in vitro. Se...

Placental abnormalities occur frequently in cloned animals. Here, we attempted to isolate trophoblast stem (TS) cells from mouse blastocysts produced by somatic cell nuclear transfer (NT) at the blastocyst stage (NT blastocysts). Despite the predicted deficiency of the trophoblast cell lineage, we succeeded in isolating cell colonies with typical morphology of TS cells and cell lines from the N...

The interaction between mouse eggs conjoined in pairs of different ages and stages of development has been examined: 1. Forty-two per cent of chimaeras formed from 8-cell eggs paired with late morulae or early blastocysts produced morphologically normal, but large, blastocysts. 2. Fusion of pairs of vitally labelled and unlabelled eggs has shown that presumptive trophoblast derived from as late...

BACKGROUND Abnormalities of oocyte morphology affect embryo quality and viability. Whether morphological abnormalities of the oocyte influence cryosurvival and further development of derived embryos is not known. The aim of this study was to compare cryosurvival and progression to the blastocyst stage of frozen-thawed embryos derived from normal and abnormal oocytes. METHODS A total of 5292 G...

The interaction between mouse eggs conjoined in pairs of different ages and stages of development has been examined: 1. Forty-two per cent of chimaeras formed from 8-cell eggs paired with late morulae or early blastocysts produced morphologically normal, but large, blastocysts. 2. Fusion of pairs of vitally labelled and unlabelled eggs has shown that presumptive trophoblast derived from as late...

BACKGROUND Embryo quality may be accurately assessed as early as the pronuclear zygote phase, as shown in recent studies. However, it is not known whether good quality zygotes are destined to become good quality cleavage stage embryos and blastocysts. METHODS In this retrospective study, 86 intracytoplasmic sperm injection-embryo transfer cycles were studied where each available embryo was sc...

Morphological changes of cultured bovine blastocysts during hatching were observed using time-lapse videomicrography in order to investigate the patterns of the hatching process that occurred in the blastocysts and to determine whether the hatching patterns differed between blastocysts developed from fresh and cryopreserved embryos. Compacted morulae (CMs) were collected from superovulation-tre...

Aberrant gene expression in somatic cell nuclear-transferred (NT) embryos due to abnormal epigenetic modifications of the donor nucleus likely accounts for much of the observed diminished viability and developmental abnormalities. We compared the expression of 13 developmentally important genes in individual 8-cell and blastocyst stage NT embryos produced from adults female cumulus cells and ad...

BACKGROUND The selection of pre-embryos for transferred is based on morphological appearance. But some poor quality cleaved embryos also can be cultured to the blastocyst stage and implanted. OBJECTIVE To assess the clinical pregnancy outcomes of blastocyst transfer which developed from poor quality embryos. MATERIALS AND METHODS A total of 109 cleaved embryos with poor quality were culture...

Teratocarcinoma cells (OTT 6050) from 129 SvSl C P mice were transferred into blastocysts from random bred Swiss albino mice. The blastocysts were placed in the uteri of foster mothers and the adults resulting from these blastocysts were studied for evidence of an effect of the transferred malignant cells. Sixty adults resulted from the experiments, and one of the adult mice that had received t...