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The cells continue to be rearranged until the shallow dip formed by invagination transforms into a deeper, narrower pouch formed by the gastrula's endoderm. This pouch narrows and lengthens to become the archenteron, a process driven by convergent extension. The open end of the archenteron is called the blastopore.
Before gastrulation, the embryo is a continuous epithelial sheet of cells; by the end of gastrulation, the embryo has begun differentiation to establish distinct cell lineages, set up the basic axes of the body (e.g. dorsal–ventral, anterior–posterior), and internalized one or more cell types including the prospective gut.
Mesoderm cells condense to form a rod which will send out signals to redirect the ectoderm cells above. This fold along the neural tube sets up the vertebrate central nervous system. The endoderm is the inner most germ layer of the embryo which gives rise to gastrointestinal and respiratory organs by forming epithelial linings and organs such ...
Epiboly in zebrafish is the first coordinated cell movement, beginning at the dome stage late in the blastula period and continuing throughout gastrulation. [3] At this point the zebrafish embryo contains three portions: an epithelial monolayer known as the enveloping layer (EVL), a yolk syncytial layer (YSL) which is a membrane-enclosed group of nuclei that lie on top of the yolk cell, and ...
At the side of the epithelium exposed to the environment (the apical side), the surface of cells shrinks, and at the side of the cell in contact with the basement membrane (the basal side), the cell surfaces expand. Thus, cells become wedge-shaped. As these cells change shape, the tissue bends in the direction of the apical surface.
Persistence of notochordal cells within the vertebra may cause a pathologic condition: persistent notochordal canal. [17] If the notochord and the nasopharynx do not separate properly during embryonic development, a depression (Tornwaldt bursa) or Tornwaldt cyst may form. [18] The cells are the likely precursors to a rare cancer called chordoma ...
"Dead Embryonic Cells" is Sepultura's second single, as well as the second of three to be released from the album Arise. A music video for the song was produced and can be found on the VHS release Third World Chaos , [ 1 ] which itself was released on DVD as part of Chaos DVD . [ 2 ]
EB differentiation begins with the specification of the exterior cells toward the primitive endoderm phenotype. [35] [36] The cells at the exterior then deposit extracellular matrix (ECM), containing collagen IV and laminin, [37] [38] similar to the composition and structure of basement membrane. In response to the ECM deposition, EBs often ...