(n.) One of the segments first formed by the division of the ovum.
Example Sentences:
(1) Mouse embryos at the two-cell stage were separated into two individual blastomeres, and one blastomere was karyotyped at the second cleavage.
(2) Cleaved embryos with 'ideal' blastomere numbers (2, 4 or 8) showed a considerably higher metaphase frequency than others.
(3) Among the most conspicuous features found were the presence of very distinct desmosome-like structures between blastomeres, and the cytoplasmic cell organelles distribution in three areas referred as: a sub-cortical, a middle and a perinuclear bands.
(4) The procedure involves bisection of single-cell eggs in a medium containing cytochalasin; fusion of egg halves with single blastomeres, induced using Sendai virus or an electrofusion apparatus; and embedding in agar, followed by culture of the reconstituted embryos in the ligated oviducts of ewes in dioestrus.
(5) Lineage tracing techniques demonstrated that those cells in the ICM of early blastocysts which did possess filaments were almost exclusively the progeny of polar 16-cell blastomeres, suggesting that these filaments were directly inherited from outside cells at the 16- to 32-cell transition.
(6) Although the posterior-vegetal blastomeres (B4.1 pair) of the 8-cell embryo have long been believed to be the sole precursors of larval muscle, recent studies using horseradish peroxidase to mark cell lineages have shown that small numbers of muscle cells originate from the anterior-vegetal (A4.1) and posterior-animal (b4.2) blastomeres of this stage.
(7) Day 6 embryos were bisected and the resulting demiembryos were stained with Hoechst 33342 and cell counts were made by counting intact blastomere nuclei.
(8) Embryos developed at a normal rate after destruction of some blastomeres.
(9) The precise temporal and spatial coincidence of the patterns of polarization and the division cycles further suggests that a mechanistic link is maintained among cell division, blastomere polarization, and probably also a heritable component of the animal-vegetal axis.
(10) Each blastomere populated all three primary germ layers.
(11) The effect of destruction of some blastomeres on subsequent cleavage in vitro was investigated in the marsupial Antechinus stuartii.
(12) We conclude that, in general, analysing blastomeres is subject to less mis-diagnosis than polar body analysis, except in the case of dominant diseases which are caused by genes which lie extremely close to the centromere.
(13) The dexiotropic rotations of blastomeres were also observed during the division of the trypsinized zygotes with the tripolar mitotic apparatus.
(14) Primordial germ cells (PGCs), which formed in 78% of cases when the presumptive ventral half to the embryo was cultured, occurred in only 48% of cases when the two ventral vegetal blastomeres were cultured alone.
(15) Nematodes have been considered the chief paradigm for determinate and cell-autonomous development, but recent experiments on the early development of Caenorhabditis elegans suggest that most blastomeres of this nematode are, in fact, determined by interactions.
(16) A fluoresceinated lineage tracer was injected into individual blastomeres of eight-cell sea urchin (Strongylocentrotus purpuratus) embryos, and the location of the progeny of each blastomere was determined in the fully developed pluteus.
(17) Although blastocysts were well expanded, distinct signs of injury to the blastomeres were present, proceeding from loss of complete blastomeres to structural changes such as large lamellar structures, dilation of smooth endoplasmic reticulum and Golgi complexes, and clumping of mitochondria.
(18) The activity of HPRT, but not of APRT, was readily detectable in single 4-cell and 8-cell blastomeres.
(19) The nucleus-like structure was partitioned into blastomeres during cleavage through a process of nuclear fission, and was maintained in a group of extraordinarily large blastomeres until the blastula stage.
(20) To distinguish between these possibilities, we compared the fates of individual frog blastomeres between Li-treated embryos and normal embryos using lineage tracers.
Ectomere
Definition:
(n.) The more transparent cells, which finally become external, in many segmenting ova, as those of mammals.
Example Sentences:
(1) The merogony follows the pattern of ectomeric schizogony.
(2) Strips of ectoderm corresponding to the presumptive branchial arches were delineated, thus defining anteroposterior 'segments' (designated here as 'ectomeres') that coincided with the spatial distribution of neural crest cells arising from the adjacent levels of the neural fold.
(3) In the course of embryonic development, cranial nerves are differentiated in concordance with the development of the metameric facial structure called 'ectomeres'.
(4) Each ectomere parallels the segmentation of the hindbrain called the 'rhombomere', in which pairs of metameric units cooperate to generate the repeating sequence of cranial branchiomotor nerves.