What is the Difference Between Archenteron and Blastocoel

The main difference between archenteron and blastocoel is that the archenteron is the primitive gut that forms during gastrulation whereas blastocoel is the cavity within the blastula that forms during blastulation. Furthermore, archenteron eventually gives rise to the lumen of the digestive tract while blastocoel diminishes in size and eventually fills up with the mesoderm.

Blastocoel, archenteron, and coelom are the three types of cavities that occur sequentially during embryonic development.

Key Areas Covered

1. What is Archenteron
     – Definition, Formation, Importance
2. What is Blastocoel
     – Definition, Formation, Importance
3. What are the Similarities Between Archenteron and Blastocoel
     – Outline of Common Features
4. What is the Difference Between Archenteron and Blastocoel
     – Comparison of Key Differences

Key Terms

Archenteron, Blastocoel, Blastulation, Digestive Tract, Gastrulation, Inner Cell Mass, Trophoblast

What is Archenteron

Archenteron or the digestive tube is the primitive gut developed during gastrulation in the developing embryo. Since it is a type of cavity formed during gastrulation, the archenteron is also known as gastrocoel. It is formed from both endoderm and mesoderm (endo-mesodermal origin).

Figure 1: Archenteron

During gastrulation, some primary mesenchyme cells of the vegetal pole (the pole of the fertilized egg containing the highest amount of yolk) enter into the cavity of the blastocoel. The remaining cells of the vegetal pole form the vegetal plate, which buckles inwards towards the blastocoel in a process known as invagination. The shallow dip formed by the invagination transforms into a deeper, narrow pouch formed by the endoderm. Blastopore is the open end of the archenteron. Then, the thin fibers called filopodia, which are formed by the primary mesenchyme cells, contract while dragging the tip of the archenteron across the blastocoel. Finally, gastrulation ends up with the fusion of the endoderm of the archenteron with the ectoderm. During the further developmental stages of the embryo, the blastopore develops into the mouth in protostomes while it develops into the anus in deuterostomes.

What is Blastocoel

Blastocoel is the cavity formed during blastulation. It is a fluid-filled cavity during the early stages of development. Since it occurs inside the blastula, blastocoel is known as the blastocyst cavity. Blastocoel is a result of cleavage of the fertilized egg at the 16-32-cell stage. Therefore, it is also known as cleavage cavity. In addition, since blastocoel separates future ectoderm from the inductive effect of the vegetal pole, it is known as a segmentation cavity.

Figure 2: Blastocyst

During the development of the mammalian embryo, the blastocyst forms from the morula stage (16-cell stage). It contains an inner cell mass in the animal pole (the opposite pole to the vegetal pole, containing the lowest amount of yolk in the fertilized egg) and an outer cell layer called trophoblast. Blastocoel occurs in between the inner cell mass and the trophoblast. It enlarges by increasing osmotic pressure, pulling the inner cell mass on one side of the trophoblast cells.

Similarities Between Archenteron and Blastocoel

• Archenteron and blastocoel are two types of cavities that occur during the embryonic development in animals.
• They perform a unique function in embryogenesis.

Difference Between Archenteron and Blastocoel

Definition

Archenteron refers to the rudimentary alimentary cavity of an embryo at the gastrula stage while blastocoel refers to the cavity of a blastula, arising in the course of cleavage. Thus, this is the main difference between archenteron and blastocoel.

Formation

Moreover, archenteron is formed during gastrulation while blastocoel is formed during blastulation.

Segmentation Cavity

Another difference between archenteron and blastocoel is that the archenteron is not a segmentation cavity since it is made up of both endoderm and mesoderm while blastocoel is a segmentation cavity since it separates future endoderm from the inductive influence of the vegetal cells.

Importance

Furthermore, blastocoel is important for the formation of archenteron while blastocoel is the first cavity formed during the embryonic development.  

Give Rise to

Also, archenteron gives rise to the lumen of the digestive tract while blastocoel diminishes in size and eventually fills up with the mesoderm. Hence, this is another difference between archenteron and blastocoel.

Conclusion

Archenteron is a cavity formed during gastrulation, developing into the lumen of the digestive cavity. However, blastocoel is the cavity formed during blastulation. It reduces its size and eventually fills up with mesoderm. Therefore, the main difference between archenteron and blastocoel is their formation and fate.

References:

1. “Archenteron.” The Columbia Encyclopedia, 6th Ed, Encyclopedia.com, 2019, Available Here
2. “Blastula.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 3 Mar. 2011, Available Here

Image Courtesy:

1. “Protovsdeuterostomes” By WYassineMrabetTalk✉This W3C-unspecified vector image was created with Inkscape. – Own work (CC BY-SA 3.0) via Commons Wikimedia  
2. “Blastocyst English” By Seans Potato Business (derivative of the source cited above) – Blastocyst.png (CC BY-SA 3.0) via Commons Wikimedia