During mouse embryogenesis initial specification of the cell fates depends on the type of division during 8- to 16- and 16- to 32-cell stage transition. A conservative division of a blastomere creates two polar outer daughter cells, which are precursors of the trophectoderm (TE), whereas a differentiative division gives rise to a polar outer cell and an apolar inner (the presumptive inner cell ...

Oxygen, an essential nutrient, is sensed by a multiple of cellular pathways that facilitate the responses to and survival of oxygen deprivation. The Caenorhabditis elegans embryo exposed to severe oxygen deprivation (anoxia) enters a state of suspended animation in which cell cycle progression reversibly arrests at specific stages. The mechanisms regulating interphase, prophase, or metaphase ar...

The genetic mechanisms governing human pre-implantation embryo development and the in vitro counterparts, human embryonic stem cells (hESCs), still remain incomplete. Previous global genome studies demonstrated that totipotent blastomeres from day-3 human embryos and pluripotent inner cell masses (ICMs) from blastocysts, display unique and differing transcriptomes. Nevertheless, comparative gen...

Experiments on the influence of the polar lobe on the development of molluscs have shown that after removal of the polar lobe cleavage is radially symmetrical and indications of bilateral symmetry do not appear (Wilson, 1904: Dentalium; Clement, 1952: Ilyanassa). In normal development the polar lobe fuses with one of the two cells of the trefoil stage, and this cell becomes the posterior side o...

We have studied the relationship between the occurrence of chromatin diminution and the developmental behavior of somatic blastomeres in early development of the nematode Parascaris univalens. A cytological and immunocytochemical analysis of chromatin diminution was performed in P. univalens embryos exposed to 'vegetalizing' (LiCl) and 'animalizing' (NaSCN) substances during early developmental...

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder with mutational heterogeneity. The scarcity of DNA from single cells in preimplantation genetic diagnosis (PGD) for DMD limits comprehensive genetic testing. Multiple displacement amplification (MDA) is reported to generate large amounts of template and give the most complete coverage and unbiased amplification to date....

At fertility clinics, living human embryos are evaluated by visual inspection of light microscopy images. The criteria to assess the quality are number of blastomeres (cells) of the embryo, regularity of size and degree of fragmentation. Today, this evaluation process is based on interpretation of 3D information projected to 2D images. It is believed that an overall improvement in the process c...

In a C. elegans embryo the third cleavages of descendants of the anterior blastomere AB of the 2-cell stage create pairs of blastomeres that develop differently. By laser ablation experiments we show that the fates of all the posterior daughters of this division depend on an induction occurring three cleavages before these blastomeres are born. The time of induction precludes a direct effect on...

The testis-specific protein Y-encoded gene (TSPY) is a Y-specific gene present in variable copy number in many mammalian species, including cattle. We tested the applicability of the TSPY gene as a Y-specific marker to predict preimplantation embryo sex in Nelore (Bos indicus) cattle. Two blastomeres were removed from each embryo. A total of 36 single blastomeres and the remaining cells o...

The quality of embryos produced by in-vitro fertilization (IVF) is variable. Many embryos contain unequal sized blastomeres and multiple cellular fragments. Embryos with excessive fragmentation have limited developmental potential both in vitro and in vivo. Histologically, some blastomeres of fragmented embryos resemble cells undergoing apoptosis as a result of programmed cell death (PCD). The ...