Human embryos are selected for transfer using morphology at the cleaving and blastocyst stages. Zygote morphology has been related to implantation and pregnancy. The aim of this study was to relate pronuclear morphology to blastocyst development. Zygotes were scored according to distribution and size of nucleoli within each nucleus. Zygotes displaying equality between the nuclei had 49.5% blast...

Asymmetric division of zygote is critical for pattern formation during early embryogenesis in plants and animals. It requires integration of the intrinsic and extrinsic cues prior to and/or after fertilization. How these cues are translated into developmental signals is poorly understood. Here through genetic screen for mutations affecting early embryogenesis, we identified an Arabidopsis mutan...

Fertilization and zygote development are obligate features of the malaria parasite life cycle and occur during parasite transmission to mosquitoes. The surface protein PFS48/45 is expressed by male and female gametes of Plasmodium falciparum and PFS48/45 antibodies prevent zygote development and transmission. Here, gene disruption was used to show that Pfs48/45 and the ortholog Pbs48/45 from a ...

BACKGROUND It is known that repeated failure of assisted reproduction treatment (ART) can be due to a paternal effect. This study was undertaken to analyse the possible relationship between ART failure and sperm DNA fragmentation. METHODS Zygote morphology and the percentage of spermatozoa with fragmented DNA (assessed by TUNEL) were compared in two groups using donor oocytes for ICSI attempt...

After fertilization, the sperm and oocyte genomes undergo extensive epigenetic reprogramming to form a totipotent zygote. The dynamic epigenetic changes during early embryo development primarily involve DNA methylation and demethylation. We have previously identified Gse (gonad-specific expression gene) to be expressed specifically in germ cells and early embryos. Its encoded protein GSE is pre...

The sexual cycle of the unicellular Chlamydomonas reinhardtii culminates in the formation of diploid zygotes that differentiate into dormant spores that eventually undergo meiosis. Mating between gametes induces rapid cell wall shedding via the enzyme g-lysin; cell fusion is followed by heterodimerization of sex-specific homeobox transcription factors, GSM1 and GSP1, and initiation of zygote-sp...

Background: Digital image processing and analysis are used for computer assisted evaluation of sperm morphology. Sperm head morphology has been identified as a characteristic that can be used to predict a male’s semen quality. On the other hand, zygote competence analysis is an importance tool to select embryo(s) for transfer. The aim of the present study is to determine zygote quality resulted...

The aim of this study is to describe the ultrastructural changes of the egg apparatus associated with fertilisation of the natural tetraploid Trifolium pratense. The pollen tube enters one of the synergids through the filliform apparatus from the micropyle. Before the entry of the pollen tube into the embryo sac, one of the synergids begins to degenerate, as indicated by increased electron dens...

This paper re-examines the question of whether quirks of early human foetal development tell against the view (conceptionism) that we are human beings at conception. A zygote is capable of splitting to give rise to identical twins. Since the zygote cannot be identical with either human being it will become, it cannot already be a human being. Parallel concerns can be raised about chimeras in wh...

Receptivity is a limited time in which uterine endometrium can establish a successful dialogue with blastocyst. This study was to investigate the effect of asynchronous embryo transfer on uterine receptivity in mice. Embryos under different stages were transferred into two oviduct sides of a recipient mouse on day 1 of pseudopregnancy. Our results showed the asynchronously transferred embryos c...