(n.) The external skin or outer layer of an animal or plant, this being formed in an animal from the epiblast. See Illust. of Blastoderm.
Example Sentences:
(1) Here we report direct measurements of protein kinase C (PKC) activity in uninduced ectoderm, and in neuroectoderm shortly after induction by the involuting mesoderm, in Xenopus laevis embryos.
(2) The Notch locus in Drosophila encodes a transmembrane protein required for the determination of cell fate in ectodermal cells.
(3) The factor was tested on Triturus alpestris by the implantation method, and on isolated ectoderm of Xenopus laevis in solution.
(4) 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.
(5) Cells falling off from ectoderm were observed in normally developing gastrulae of the newt, Cynops pyrrhogaster, in light microscopic examination.
(6) Anhidrotic ectodermal dysplasia is characterized by an absence of seromucous glands in the oropharynx and tracheobronchial tree, making children with this disease prone to viral and bacterial respiratory infections.
(7) The positive reaction for keratin and vimentin confirmed the presence of ectodermal and mesodermal elements respectively in the tumor.
(8) Examination of the two types of tissue fragments revealed that IS-treated ICMs almost invariably retained viable endoderm cells whereas MS-isolated ectoderms did so only exceptionally.
(9) 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).
(10) Ectoderm from Cynops pyrrhogaster reacts like that of Ambystoma when exposed to LiCl, but like Triturus ectoderm it is insensitive to cyclic nucleotides.
(11) Several mouse mutants in the distal region of the mouse t-complex affecting blastocyst and embryonic ectoderm formation also map to this region.
(12) PTN mRNA was also strongly expressed in the basal layers of the tongue epithelium, which is the only epithelium and ectodermal derivative to express PTN mRNA, and this only after birth.
(13) These genes encode membrane proteins with epidermal growth factor repeats and are essential in the decision of an embryonic ectodermal cell to take on the fate of neuroblast or epidermoblast.
(14) We have found that competence of the ectoderm to respond to induction is lost at the same early neurula stage for all three marker genes.
(15) Multiple hamartoma syndrome, also known as Cowden's disease, is a rare genodermatosis with multiple organ system involvement affecting tissues derived from ectodermal, endodermal, and mesodermal tissue layers.
(16) From the right wing bud of stage 19 and 20 (HH) embryos the rim ectoderm was removed in four ways: all of the rim, the anterior third, the middle third (most of the A.E.R.
(17) During feather follicle formation, N-CAM was expressed in the dermal papilla and was closely apposed to the L-CAM-positive papillar ectoderm, while the dermal papilla showed no evidence of laminin or fibronectin.
(18) Initially each primordium forms a shallow depression in the ectodermal surface.
(19) From stage 110 on, a basement membrane differentiates beneath a one-cell thick subperipheral layer, which thus becomes the ectodermal basal layer, the prospective epidermal basal layer.
(20) CAT mRNA was observed in gut, mesenchyme cells and oral ectoderm in these embryos.
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.