Changes in the activities of nitric oxide synthase (NOS) during embryonic development, and the distribution of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) isoforms were examined in unfertilized mouse oocytes at the second meiotic metaphase (MII) stage and in fertilized mouse embryos during preimplantation development. In addition, the effects of NOS inhib...

X-chromosome inactivation (XCI) equalizes gene expression between the sexes by inactivating one of the two X chromosomes in female mammals. Xist has been considered as a major cis-acting factor that inactivates the paternally derived X chromosome (Xp) in preimplantation mouse embryos (imprinted XCI). Ftx has been proposed as a positive regulator of Xist. However, the physiological role of Ftx i...

DNA methylation reprogramming plays important roles in mammalian embryogenesis. Mammalian somatic cell nuclear transfer (SCNT) embryos with reprogramming defects fail to develop. Thus, we compared DNA methylation reprogramming in preimplantation embryos from bovine SCNT and in vitro fertilization (IVF) and analyzed the influence of vitamin C (VC) on the reprogramming of DNA methylation. The res...

Three experiments were conducted to examine the in vitro development of preimplantation embryos from the prolific Chinese Meishan pig. Experiment 1 was conducted to assess whether Meishan embryos would develop in vitro and retain their viability, whereas Exp. 2 and 3 examined the developmental pattern of Meishan embryos. In all three experiments, Yorkshire embryos served as a contemporary compa...

background: this study was designed to develop a new co-culture system, assess the effect of luteinizing hormone (lh) using sequential media to promote development and increase the quality of 2-cell murine embryos through the 8-16 cell stage to morula and blastocyst stages. materials and methods: monolayers for co-culture were prepared from ovine oviduct epithelial cells (ooec) in dmem/f12 medi...

We have constructed amplified cDNA preparations from replicate samples of human oocytes and individual preimplantation embryos. Differential display of the cDNA preparations shows disparate patterns of gene expression in the individual embryos at all stages of preimplantation development. The variation in patterns of genes expressed is in part due to the low starting cell number undergoing the ...

Gap junctional intercellular coupling allows cells to share low molecular weight metabolites and second messengers, thus facilitating homeostatic and developmental processes. Gap junctions make their appearance very early in rodent development, during compaction in the eight-cell stage. Surprisingly, preimplantation mouse embryos lacking the gap junction protein connexin 43 develop normally and...

We have detected a novel splice variant of the hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene in two human oocytes and four preimplantation embryos from the 4-cell to the 8-cell stage of development. The novel HPRT transcript lacks exons 4, 5 and 6 of the normal HPRT gene. The same parental origin for the two oocytes and two of the preimplantation embryos, in which the alternativel...

Genetic aberrations are commonly seen in human preimplantation embryos. Non-disjunction and premature division of a chromosome are common in both meiosis and mitosis divisions. The expected result for meiotic aneuploidies is full aneuploidy in the later stages whereas mosaicism is the most frequent event in the cleavage and blastocyst stages. The main causes for mosaicism are post-zygotic event...