gastrula


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gastrula

 [gas´troo-lah]
an embryo in the stage following the blastula stage; the simplest type consists of two layers of cells, the ectoderm and entoderm, which have invaginated to form the archenteron and an opening, the blastopore.

gas·tru·la

(gas'trū-lă),
The embryo in the stage of development following the blastula or blastocyst; in lower forms with minimal yolk, it is a simple double-layered structure consisting of ectoderm and endoderm enclosing the archenteron, which opens to the outside by way of the blastopore; in forms with considerable yolk, the configuration of the gastrula is greatly modified owing to the persistence of the yolk throughout the gastrulation process. In human embryos, the gastrula stage occurs in the third week as the embryonic disk becomes trilaminar.
Synonym(s): invaginate planula
[Mod. L. dim. of G. gastēr, belly]

gastrula

/gas·tru·la/ (gas´troo-lah) the embryo in the stage following the blastula or blastocyst; the simplest type consists of two layers of cells, the ectoderm and endoderm, which have invaginated to form the archenteron and an opening, the blastopore. In human embryos the gastrula stage occurs during the third week, as the embryonic disc becomes trilaminar, establishing the ectoderm, mesoderm, and endoderm.

gastrula

(găs′trə-lə)
n. pl. gastru·las or gastru·lae (-lē′)
An embryo at the stage following the blastula, after the movement of cells results in the formation of the three germ layers, ectoderm, mesoderm, and endoderm.

gas′tru·lar (-lər) adj.

gastrula

[gas′troo͡lə]
Etymology: Gk, gaster, stomach
the early embryonic stage formed by the invagination of the blastula. The cup-shaped gastrula consists of an outer layer of ectoderm and an inner layer of mesentoderm that subsequently differentiate into the mesoderm and endoderm. See also blastula, embryonic layer.

gas·tru·la

(gas'trū-lă)
The embryo in the stage of development following the blastula or blastocyst formation; in the human embryo, the absence of yolk allows for a rapid, direct "putting in place" of the germ layers (ectoderm and endoderm), which are derived from the pluripotential embryonic disc.
[Mod. L. dim. of G. gastēr, belly]

gastrula

The stage in the development of an EMBRYO following the BLASTULA stage when the ECTODERM, ENDODERM and primitive GUT have developed.

gastrula

a stage in embryonic development in which the BLASTULA has invaginated, so giving rise to a two-layered embryo by a process of gastrulation. see ARCHENTERON.

gastrula

an embryo in the stage following the blastula stage; the simplest type consists of two layers of cells, the ectoderm and entoderm, which have invaginated to form the archenteron and an opening, the blastopore.
References in periodicals archive ?
The transition towards an aerobic metabolism at gastrula stage in living organisms correlate from an Evoecotoxicological perspective with a period of major progresses during the evolutionary process of multicellular life forms in the rising free oxygen environment.
However, mitochondrial activation of aerobic metabolism at the gastrula stage seems to support the assumption that these organelles existed in eukaryotic cells long in advance of the achievement of oxidative phosphorylation.
In the embryonic stages of gastrula and neurula, active cell movements lead to disruption of tissue topography with production of empty spaces in the morphogenetic field by electrical decoupling of intercellular joints.
2] at early gastrula stages for the number of TUNEL-stained cells in cranial, trunk, tail, and enteric regions (Figure 7).
Evaluations were then conducted at the mid-blastula 1 stage, late blastula 1 or 2 through early gastrula 1 stage, late gastrula-early prism stage, or prism stage; the characteristics of each stage have been described previously (51).
The 9 stages of development (oviposition, first division of cleavage, 4-cell stage, 8-cell stage, morula, blastula, gastrula, motion of larvae by velar rudiment, and early veliger stage) proposed by Chia and Koss (1978) and Buckland-Nicks et al.
blastula, gastrula, trochophore, veliger, and creeping larvae) are also shown in Table 1.
During the first 24 h, different stages of cell division were observed, followed by a ciliated blastula, a gastrula, and a trochophore stage.
Briefly, from 24-28[degrees]C, the extrusion of the polar bodies occurred within 10 min AF, first cleavage occurred ar 1 h AF, morula stage at 3 h AF, cilliated gastrula at 7 h AF, early trochophore at 10 h AF, late trochophore 20 h at AF, and D shaped-larvae with well-developed velum developed at 23-24 h AF.
Time Lapse After Fertilization Developmental Stage (hours) Gastrula 24 Intra capsular "trocophore" 48 Free-swimming "veliger" 72