(n.) That stage in the development of the ovum in which the outer cells of the morula become more defined and form the blastoderm.
Example Sentences:
(1) The activity was maximum at the 16-32-cell stage and then decreased to a minimum at the mesenchyme blastula stage.
(2) In Lytechinus pictus, the protein cannot be detected in eggs or in embryos until the mesenchyme blastula stage.
(3) In the present study, ectodermal explants from Xenopus blastulae were shown to have high affinity binding sites for 125I-aFGF (Kd = 1.4 X 10(-10) M).
(4) In blastula nuclei, over half of the RNA synthesis is effected by polymerase II (inhibited by alpha-amanitin), the proportion remaining roughly constant with increasing ionic strength.
(5) The embryos incubated in vitro at the from blastula stage are characterized by the sharp activation of protein synthesis and the vegetal-animal gradient of protein synthesis, as well as in the control embryos; such embryos gastrulate and proceed to primary differentiation.
(6) Scanning electronmicroscopy examination showed that the morphology of NCH blastula cells, which were obtained from the combination of Tilapia nucleus and goldfish cytoplasm, manifested obviously abnormal features and the cells were arrested at different stages of cell disintegration.
(7) Measurements of absolute transcript abundance show that collagen mRNA is present in blastula primary mesenchyme cells at 600-700 copies per cell and at about fourfold lower amounts in other mesenchyme cells.
(8) beta-Catenin, recognized by an anti-arm antibody, is also present in the fertilized egg and in blastula-stage embryos.
(9) The tandemly repeated genes were expressed at a higher rate in blastula than in gastrula stage relative to the single-copy gene, when the two genes were injected into sea urchin zygotes.
(10) As a result, there is a loss of the 'compacted' epithelial surface of the blastula, an inability to close a wounded surface and defective gastrulation.
(11) This aggregation is prevented by Fab fragments obtained by immunization with purified membranes from blastula embryos.
(12) In S. purpuratus, the Hbox1 gene product probably is not involved in initial specification of cell fate, as this message does not achieve a significant fraction of its peak abundance until almost hatching blastula stage, well after the time aboral ectoderm cells have initiated a tissue-specific program of gene expression.
(13) First, using eggs at the blastula stage, the proper concentration of cadmium to which the eggs should be exposed was estimated.
(14) Actinomycin D is excluded from unfertilized eggs and developing embryos of the sea urchin Arbacia punctulata until the blastula hatches.
(15) We are investigating the mechanism by which animal cells of an amphibian blastula are induced to differentiate as muscle after contact with blastula vegetal cells.
(16) By the early blastula stage, most of the maternal tubulin sequences were associated with polysomes.
(17) The dynamics of protein synthesis in the loach embryos has been studied by means of autoradiography at the stages of cleavage, blastula and gastrula.
(18) The same material added to dissociated blastula cells, or to embryos at the blastula stage, stimulates skeleton formation and pigment cell differentiation.
(19) New embryonic rRNA transcripts are first detectable at the very early blastula stage.
(20) 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.
Epiblast
Definition:
(n.) The outer layer of the blastoderm; the ectoderm. See Blastoderm, Delamination.
Example Sentences:
(1) Expansion of the cell sheet following attachment, and the fusion of epiblasts advancing toward each other, does not require the presence of mineralocorticoid.
(2) At the midgastrula stage the epiblast cells have the highest dry weight due to the highest protein concentration in the cytoplasm and the biggest cell volume.
(3) Proliferation occurs throughout the extra-embryonic epiblast during the expansion period.
(4) These observations are consistent with an epiblast origin for the avian germ line, and are strikingly similar to those reported for the early mouse embryo using the same antibody (Hahnel & Eddy, 1986).
(5) IGFBP-2 mRNA was detected throughout the epiblast of the egg cylinder as early as e7, when IGF-II expression was restricted to trophectoderm and other extraembryonic cells.
(6) It is also noted that the inadequate differentiation of the epiblast and endoderm would not have been apparent without microscopic examination.
(7) Both X chromosomes continued to replicate synchronously in the embryonic ectoderm or epiblast at this stage.
(8) The resulting space is not homologous with the primordial amniotic cavity; instead, it is a transitory tropho-epiblastic cavity.
(9) After the yolk has been covered, the epiblast continues to grow, with proliferation restricted largely to band just distal to the advancing edge of the area vasculosa.
(10) Primordial germ cells in the mouse are known to be derived from the epiblast.
(11) In general, the dorsoventral orientation of the previously induced epiblast was retained, but the orientation of the competent epiblast cells was more flexible and could be influenced by the neighbouring neuralised cells.
(12) The results of this study show that the epiblast cells of chick blastoderm at Hamburger-Hamilton stage 1 contain macrobodies which themselves contain particles resembling the 'lining bodies' described by Bellairs.
(13) At one time presumed to be derived from a common "neural" ancestor, all are now deemed to be "neuroendocrine-programmed," arising either in the embryonic epiblast itself or in one of its principal descendants.
(14) Epiblastic cells never gave rise to skeletal myotubes.
(15) The definitive amniotic epithelium forms by the upfolding and mitotic proliferation of the margins of the epiblastic disc; this process is completed in 11-day rhesus, and 9-day human, blastocysts.
(16) At 108 h and 120 h pc the polar trophoblast (Rauber's layer) is an intact epithelium overlying the epiblast of the inner cell mass.
(17) The epiblast cells of the optic bud do not migrate into the brain and the lamina is formed by the proliferation of the central imaginal disc.
(18) By the time of primitive streak formation (stage 4-5) the dorsal surface of the epiblast displayed increased binding sites, while the frequency of sites on the ventral surface of the endoblast was reduced.
(19) A microinjection technique is described for fate mapping the epiblast of avian embryos.
(20) Injection in situ of a short-term lineage label (horse radish peroxidase) into single epiblast cells at 6.7 days p.c.