In the present study we describe the localization of proteasomes in human oocytes, apoptotic preimplantation embryos, and triploid preimplantation embryos by means of immunolabelling with the MCP21 monoclonal antibody detected by confocal microscopy. While in the oocytes proteasomes are scattered throughout the cytoplasm, in the pronuclear zygote they appear to concentrate at the periphery of t...

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...

Spatiotemporal expression of transcription factors is crucial for genomic reprogramming. Pou5f1 (Oct4) is an essential transcription factor for reprogramming. A recent study reported that OCT4A, which is crucial for establishment and maintenance of pluripotent cells, is expressed in oocytes, but maternal OCT4A is dispensable for totipotency induction. Whereas another study reported that OCT4B, ...

Imprinted genes are characterized by expression of only one of the two alleles according to its inheritance from the mother or the father. This mono-allelic expression must arise from primary differential epigenetic modification of the parental alleles of the imprinted gene in the spermatozoon and the oocyte. Most of the information on the onset of imprinted gene expression, and on the molecula...

background: genome instability is a main cause of chromosomal alterations in both somatic and germ cells when exposed to environmental, physical and chemical genotoxicants. germ cells especially spermatozoa are more vulnerable to suffering from dna damaging agents during spermatogenesis and also more potent in transmitting genome instability to next generation. methods: to investigate the effec...

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...

We found retardation of preimplantation embryo growth after exposure to maternal restraint stress during the preimplantation period in our previous study. In the present study, we evaluated the impact of preimplantation maternal restraint stress on the distribution of inner cell mass (ICM) and trophectoderm (TE) cells in mouse blastocysts, and its possible effect on physiological development of...

The cells in the preimplantation mammalian embryo undergo several rounds of fast cell division. Whether the known DNA repair pathways are active during these early stages of development where cell division is of primary importance, has not been fully established. Because of the important role of phosphorylated H2A.X (gammaH2A.X) in the DNA damage response as well as its putative role in assembl...