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The archenteron, also called the gastrocoel, the primitive digestive tube or the primitive gut, is the internal cavity of the primitive gastrointestinal tract that forms during gastrulation in a developing animal embryo. It develops into the endoderm and mesoderm of the animal.
During gastrulation cells migrate to the interior of the blastula, subsequently forming two (in diploblastic animals) or three (triploblastic) germ layers. The embryo during this process is called a gastrula. The germ layers are referred to as the ectoderm, mesoderm and endoderm.
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.
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 ...
Koller's sickle induces primitive streak and Hensen's node, which are major components of avian gastrulation. Avian gastrulation is a process by which developing cells in an avian embryo move relative to one another in order to form the three germ layers (endoderm, mesoderm, and ectoderm).
Reptile gastrulation differs slightly from birds and mammals. Reptiles exhibit bi-modal gastrulation during embryogenesis and lack a primitive streak. Bi-modal gastrulation is characterized by involution of the cells in the anterior and lateral regions of the blastopore and ingression of the cells of the blastopore plate in the posterior region ...
During gastrulation, deuterostome embryos' anus is given first by the blastopore while the mouth is formed secondarily, and vice versa for the protostomes In deuterostomes, the developing embryo's first opening, the blastopore , becomes the anus , while the gut eventually tunnels through the embryo until it reaches the other side, forming an ...
In birds, the organizer is known as Hensen's node, named after its discoverer Victor Hensen. In other amniotes, it is known as the primitive node. In amphibians, it is known as the Spemann-Mangold organizer, named after Hans Spemann and Hilde Mangold, who first identified the organizer in 1924. [1]) In fish, it is known as the embryonic shield. [2]