Fate of blastopore, Biology

Fate of Blastopore

Cleavage results in the formation of a ball of cells called morula (resembling mulberry hence the name). A space appears in the morula changing it to a hollow blastula. The central cavity is called the blastocoel and the layers of cells surrounding it the blastoderm. Invagination or infolding of the blastoderm gives rise to a double walled gastrula. The cavity of this double walled cup is called archenteron and the opening of the archenteron to the outside is called the blastopore.

2395_Fate of Blastopore.png

Figure: Early embryology of a nemertean worm a protostome

As the gastrula develops further, 'parts of the embryo give rise to different structures to ultimately form a complete young one. In platyhelminths, nematodes, annelids, arthropods and molluscs that have spiral cleavage, the embryonic blastopore forms the mouth of the animal and the anus is formed secondarily. Because the mouth forms first these animals are included in 'Protostomia' (mouth first) division of Animal Kingdom. In echinoderms, chaetognaths, hemichordates and chordates where radial cleavage takes place, the blastopore forms the anus of the animal and the mouth is formed secondarily, as an independent opening on the body wall as seen in Figure. Therefore, these animals are included in 'Deuterostomia' (mouth second), division of the Animal Kingdom.

The fate of the blastopore thus determines two fundamental lines of evolution. The protostomes in which the cleavage is generally mosaic (determinate and spiral) and the Deuterostomes in which the cleavage is usually regulative (radial and indeterminate) type.

Posted Date: 1/15/2013 1:58:06 AM | Location : United States







Related Discussions:- Fate of blastopore, Assignment Help, Ask Question on Fate of blastopore, Get Answer, Expert's Help, Fate of blastopore Discussions

Write discussion on Fate of blastopore
Your posts are moderated
Related Questions
Who is the founder of theory survival of the fittest ?

Q. What are some important neurotransmitters? The following are some neurotransmitters: serotonin, noradrenaline (norepinephrine), histamine,acetylcholine, adrenaline (epinephr

Types of Stress Caused by Freezing Thus, freezing can cause the following kinds of stresses Lowering of temperature to suboptimum thus reducing the activity of mo

Q. Why is the AIDS treatment often done with a drug cocktail? The treatment of obtain immune deficiency syndrome is often done with one or more anti-retroviral drugs of differe

What is the name of the cytoplasm division in the end of mitosis? What are the differences in this process between animal and plant cells? Cytoplasm division happens after telo

A solid compound was found to contain 42.11% C, 51.46%O and 6.43% H by weight. The molecular weight of the compound was 341. What is the molecular formula of the compound?

Explain Micafungin sodium Micafungin sodium (Mycamine - Astellas), the second echinocandin antifungal1 to become available in the US, has been approved by the FDA for intraveno

Emerging and New Generation By-Products Oil palm by-products are good examples of NCFR which are becoming increasingly important new feeds. This is associated with the rapidly

a) What are the two types of chemical compound which combine to form a lipid? b) What elements are present in a lipid? a) Lipids are formed from the combination of

What is Risk  Risk  :  A function of the probability of an adverse effect and  the magnitude of that  effect,  consequential to hazard(s)  in food.