Archenteron
Encyclopedia
The primitive gut that forms during gastrulation
in the developing blastula
is known as the archenteron. It develops into the digestive tract of an animal.
As primary mesenchyme cells detach from the vegetal pole in the gastrula and enter the fluid filled cavity in the center (the blastocoel), the remaining cells at the vegetal pole flatten to form a vegetal plate. This buckles inwards towards the blastocoel in a process called invagination
. 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 narrowing and lengthening of the archenteron is driven by convergent extension
. The open end of the archenteron is called the blastopore
.
The filopodia
--thin fibers formed by the mesenchyme cells--found in a late gastrula contract to drag the tip of the archenteron across the blastocoel. The endoderm of the archenteron will fuse with the ectoderm
of the blastocoel wall. At this point gastrulation is complete, and the gastrula has a functional digestive tube.
The indentation that is actually formed is called the lip of the blastopore in amphibian
s and fish
, and the primitive streak
in bird
s and mammal
s. Each is controlled by the dorsal blastopore, and primitive node (also known as Hensen's node), respectively.
Gastrulation
Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a trilaminar structure known as the gastrula. These three germ layers are known as the ectoderm, mesoderm, and endoderm.Gastrulation takes place after cleavage...
in the developing blastula
Blastula
The blastula is a hollow sphere of cells formed during an early stage of embryonic development in animals . The blastula is created when the zygote undergoes the cell division process known as cleavage. The blastula is preceded by the morula and is followed by the gastrula in the developmental...
is known as the archenteron. It develops into the digestive tract of an animal.
Formation of the Archenteron in Sea Urchins
- See GastrulationGastrulationGastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a trilaminar structure known as the gastrula. These three germ layers are known as the ectoderm, mesoderm, and endoderm.Gastrulation takes place after cleavage...
.
As primary mesenchyme cells detach from the vegetal pole in the gastrula and enter the fluid filled cavity in the center (the blastocoel), the remaining cells at the vegetal pole flatten to form a vegetal plate. This buckles inwards towards the blastocoel in a process called invagination
Invagination
Invagination means to fold inward or to sheath. In biology, this can refer to a number of processes.* Invagination is the morphogenetic processes by which an embryo takes form, and is the initial step of gastrulation, the massive reorganization of the embryo from a simple spherical ball of cells,...
. 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
Endoderm
Endoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the ectoderm and mesoderm , with the endoderm as the intermost layer...
. This narrowing and lengthening of the archenteron is driven by convergent extension
Convergent extension
Convergent extension, or Convergence and Extension, is the process by which the tissue of an embryo is restructured to converge along one axis and extend along a perpendicular axis by cellular movement...
. The open end of the archenteron is called the blastopore
Blastopore
A blastopore is an opening into the archenteron during the embryonic stages of an organism. The distinction between protostomes and deuterostomes is based on the direction in which the mouth develops in relation to the blastopore...
.
The filopodia
Filopodia
Filopodia are slender cytoplasmic projections that extend beyond the leading edge of lamellipodia in migrating cells. They contain actin filaments cross-linked into bundles by actin-binding proteins, e.g. fascin and fimbrin. Filopodia form focal adhesions with the substratum, linking it to the...
--thin fibers formed by the mesenchyme cells--found in a late gastrula contract to drag the tip of the archenteron across the blastocoel. The endoderm of the archenteron will fuse with the ectoderm
Ectoderm
The "ectoderm" is one of the three primary germ cell layers in the very early embryo. The other two layers are the mesoderm and endoderm , with the ectoderm as the most exterior layer...
of the blastocoel wall. At this point gastrulation is complete, and the gastrula has a functional digestive tube.
The indentation that is actually formed is called the lip of the blastopore in amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
s and fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, and the primitive streak
Primitive streak
The primitive streak is a structure that forms during the early stages of avian, reptilian and mammalian embryonic development.-Introduction:...
in bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s and mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s. Each is controlled by the dorsal blastopore, and primitive node (also known as Hensen's node), respectively.
