Fate of blastopore, Biology

Assignment Help:

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.


Related Discussions:- Fate of blastopore

Explain wild-type fruitfly drosophila melanogaster, A cross among wild-type...

A cross among wild-type fruitfly Drosophila melanogaster  [normal bristles and grey body (s+s, e+ e)] with a mutant fly [short bristles and ebony body (ss ee)] produces following p

What is the probability the child will have pku, PKU is a recessive disorde...

PKU is a recessive disorder. Suppose two people who were heterozygous for PKU married and had a child. What is the probability that the child will have PKU?

Disorder of adrenal function, Disorder  of Adrenal Function: The diso...

Disorder  of Adrenal Function: The disorders of  adrenal function may lead  to acute and chronic  .adrenocortical insufficiency. Let  us briefly  describe each  one as follows

The protective structures of the central nervous system, What are the prote...

What are the protective structures of the central nervous system present in vertebrates? In vertebrates the brain and the spinal cord are protected by membranes, the meninges,

Differentiate individual atoms true or false, What is the first step normal...

What is the first step normally taken when you look through the oculars? The nuclei of the cheek cells have been stained using a special dye so that they appear purple. What is the

#title.Homework., Why do you think it is necessary for physicians to have s...

Why do you think it is necessary for physicians to have so many different terms that describe fractures (compound, comminuted, transverse, greenstick, etc.)?

Embryology, what is the full name of Balfour in Balour''s law of cleavage?

what is the full name of Balfour in Balour''s law of cleavage?

Explain metabolism of iron, Explain Metabolism of Iron? In this sub-sec...

Explain Metabolism of Iron? In this sub-section, we will study how body gets its iron supply, how iron is transported and utilized by the various tissues and how iron balance i

Anaplasia - characteristics define cancer, Anaplasia - Characteristics Defi...

Anaplasia - Characteristics Define Cancer Anaplasia is a structural abnormality where cells resemble primitive or embryonic tissue in which adult functions are diminished or t

What is the improper implant type in improper bone type, Improper Implant t...

Improper Implant type in Improper Bone Type In routine sites with good quality bone, the clinician should prefer implants without any superadded HA coatings and avoiding their

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd