(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.
Gastrulation
Definition:
(n.) The process of invagination, in embryonic development, by which a gastrula is formed.
Example Sentences:
(1) Birthdates of neurons were obtained from autoradiograms of animals receiving tritiated thymidine from gastrulation through 1 month after metamorphosis.
(2) Evx-1 RNA is first detected shortly before the onset of gastrulation in a region of ectoderm containing cells that will soon be found in the primitive streak.
(3) 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.
(4) Thus, the area with separated HL, which is restricted to the region of the PMC released at the stage of PMC ingression, spreads almost entirely throughout the area of the indenting vegetal plate at gastrulation.
(5) On the basis of hystological studies a description of fission and gastrulation in Microsomacanthus paramicrosoma (gasowska, 1931) is given.
(6) This contrasts with embryos ventralized by UV-irradiation and suggests that XBMP-4-induced ventralization occurs after the onset of gastrulation.
(7) Several lines of experimental evidence indicate that contact with the animal pole locus, or "target" region, is crucial for the change in phenotype of the SMCs: (1) the phenotypic change can be induced precociously by bringing the animal pole region within reach of the tip of the archenteron early in gastrulation.
(8) Gastrulation is accompanied by a sharp increase in the AChE activity which was most pronounced in anterior hypoblast.
(9) In the present study, it was found that cytotactin is first present in the gastrulating chicken embryo.
(10) Experiments are described that examine the state of organisation of the presumptive mesoderm and ectoderm of the Xenopus embryo at stages up to the onset of gastrulation.
(11) 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.
(12) (d) Tenascin blocks cell adhesion to FN in vitro and gastrulation in vivo.
(13) In contrast, in vitro activity of mannosylphosphoryldolichol synthase, another enzyme in the pathway of N-linked glycosylation, was maximal in membranes from egg and embryos in the early stages of development and declined prior to gastrulation.
(14) As an immediate consequence of neural induction during gastrulation, some neuroectodermal cells acquire the ability to develop a number of specific neuronal and astroglial features, without requiring subsequent chordamesodermal cues.
(15) After gastrulation additional novel non-oogenetic proteins were synthesized for most stages examined.
(16) An analysis of changes in cell shape during the initial phase of gastrulation indicates that there is a stage-dependent shift from cells being columnar to having their apices skewed toward the vegetal plate and an increase in the proportion of cells having basal processes during gastrulation.
(17) In view of the hypocalcaemic properties of calcitonin and the importance of calcium ions in cell aggregation, this phenomenon has been attributed to an alteration in cell adhesion which results in faulty cell migration during gastrulation with consequent abnormalities of the prechordal region of the archenteron roof and the overlying neural plate.
(18) Microtubule distribution was examined in whole mounts of Drosophila embryos from the cellularization of the syncytial blastoderm (stage 6) to the completion of the gastrulation (stage 7) by fluorescence microscopy.
(19) These changes in the dynamic properties of the lipid probe HEDAF during gastrulation suggest that the lipid phase of the plasma membrane of these ectodermal cells undergo structural changes.
(20) In Lytechinus, the late appearing histone, H1g, begins to be synthesized at gastrulation.