(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.
Gastrula
Definition:
(n.) An embryonic form having its origin in the invagination or pushing in of the wall of the planula or blastula (the blastosphere) on one side, thus giving rise to a double-walled sac, with one opening or mouth (the blastopore) which leads into the cavity (the archenteron) lined by the inner wall (the hypoblast). See Illust. under Invagination. In a more general sense, an ideal stage in embryonic development. See Gastraea.
(a.) Of or pertaining to a gastrula.
Example Sentences:
(1) Results obtained from cumulative labeling and pulse-labeling and chase experiments with cells from late gastrulae, yolk plug-stage embryos, and neurulae showed that the 30S RNA is an intermediate in rRNA processing and is derived from 40S pre-rRNA and processed to 28S rRNA.
(2) Cells falling off from ectoderm were observed in normally developing gastrulae of the newt, Cynops pyrrhogaster, in light microscopic examination.
(3) Among such genes, particular interest is focused on three genes encoding putative transcription factors that are expressed specifically in the Spemann organizer region of the gastrula.
(4) Their synthesis is first detectable in stage IV oocytes and continues throughout early embryogenesis until the late gastrula.
(5) 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.
(6) RA was applied for one hour at concentrations ranging from 10(-9) to 10(-6) M to embryos at 50% epiboly, the midgastrula stage, and at 10(-7) M to embryos at early and late gastrula stages.
(7) In gastrulae, spectrin accumulates near the embryo surface, especially at the forming amnioproctodeal invagination and cephalic furrow.
(8) The dynamics of protein synthesis in the loach embryos has been studied by means of autoradiography at the stages of cleavage, blastula and gastrula.
(9) GAD activity was undetectable at the early gastrula stage (stage 8a) and was slightly measurable at the early neurula stage (stage 14- onset of the culture).
(10) However, we established an enhanced level of [14C]acetate incorporation at the time of extensive gene activation during gastrulation as well as some quantitative differences in the pattern of acetylation during gastrula and organogenesis.
(11) RNase protection assays demonstrate that transcripts encoding alpha, gamma, and delta subunits are coordinately expressed at late gastrula and that the amount of each transcript increases in parallel with muscle-specific actin mRNA during the ensuing 12 h. After the onset of muscle activity the level of actin mRNA per somite remains relatively constant, whereas the level of alpha subunit and delta subunit transcripts decrease fourfold per somite and the level of gamma subunit transcript decreases greater than 50-fold per somite.
(12) When the supernatant proteins from eggs and gastrulae were subjected to size-exclusion HPLC the neural inducing activity was eluted in different size classes, suggesting a limited proteolysis of a precursor during early embryogenesis.
(13) Isolated neuroblasts from gastrula-stage Drosophila embryos divide and differentiate in vitro to produce clonally derived clusters of neurons.
(14) In both fish embryos, the COI and COII transcripts declined gradually after fertilization until late-blastula stage and then increased in early gastrula stage.
(15) Three of these clones are not represented in the maternal RNA population but are activated at the late gastrula stage; the other three increase from a maternal base.
(16) This led to an attempt to discover the molecular character of cell action by means of transfilter induction in early gastrula ectoderm of Xenopus laevis.
(17) We have demonstrated that a 'wave' of DNA synthesis occurs in the neurectoderm of Xenopus laevis gastrula.
(18) When Xenopus blastula or early gastrula ectoderm is disaggregated and cells are kept dispersed for up to 5 h prior to reaggregation, the resulting spheres will differentiate into large neural structures.
(19) Yolky tissue from the vegetal hemisphere of the gastrula or the archenteron floor of the neurula synthesized mainly polydisperse material of high molecular weight rather than discrete glycoproteins.
(20) The transgenome replicates intensively during the course of early development (until the blastula--early gastrula stages), but later the replication slows down which results in the elimination of the transgenome from the majority of embryos at more advanced stages.