For all species of cidaroids in which early development has been described, the blastomeres
are widely spaced.
reported that the rate of survival tends to increase with the increasing number of blastomeres
and cell stage cleavage embryos (57, 58).
Sexing of preimplantation mouse embryos by measurement of X-linked gene dosage in a single blastomere
The separated blastomeres
were coated with an artificial zona pellucida and placed in the culture medium used for in vitro fertilization (IVF).
Likewise, if these factors are distributed to both blastomeres
during first cleavage by equalizing this division, twinning occurs via the production of two D quadrants (Tyler, 1930; Henry and Martindale, 1987; Dorresteijn et at, 1987; Render, 1989).
As the mitotic apparatus of the large blastomere
became organized with chromosomes at the metaphase plate, the chromosomes of the three small blastomeres
were less condensed and the aster not completely segregated.
The increase of cell segmentation enhances the degree of compaction between blastomeres
and marks the end of the ball stage (Wolpert et al.
Vacquier and Mazia (1968a, b) hypothesized that the hyaline layer plays a greater role in holding blastomeres
together in regular sea urchins than in sand dollars.
Spindle  and ooplasmic transfer [6,7] pre-fertilisation, and pronuclear  and blastomere
nucleus transfer  post-fertilisation, have been explored to achieve this.
Aneuploidies of the blastomeres
were analyzed according to the depth of the heterozygous SNP alleles.
a (formerly called FoxA-a) is expressed in the animal-anterior, vegetal-anterior and vegetal-posterior blastomeres
It reviews current methods and experiences, then provides an atlas of normal and abnormal human preimplantation development; micromanipulation and biopsy of polar bodies, blastomeres
, and blastocytes; nuclear transfer techniques and the prospect for artificial gamete formation; and preimplantation diagnosis for aneuploidies, translocations, and single-gene disorders.
Specific topics include germ-cell differentiation from pluripotent cells, adult stem-cell population in the human testis, embryonic stem cells from blastomeres
maintaining embryo viability, in utero hematopoietic cell transplantation, and the metabolic framework of pluripotent stem cells and potential mechanisms of regulation.
Embryos were scored according to the number, size of the blastomeres
and the amount of anucleate fragmentation: type 1, embryos had equal-sized blastomeres
and anucleate fragmentation; type 2, embryos had blastomeres
unequal in size and less than 20% fragmentation; type 3, embryos had 20%-50% fragmentation; and type 4, embryos had greater than 50% fragmentation.
Preclinical validation of a microarray method for full molecular karyotyping of blastomeres
in a 24-h protocol.