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

Determine effective half life and value of effective decay, 1. By direct me...

1. By direct measurement of the activity of the thyroid gland in several patients who had received 131 I for diagnostic purposes, it was observed that the biological elimination h

What are the main cellular functions of potassium, What are the main cellul...

What are the main cellular functions of potassium? Besides being significant for the osmotic regulation and for the acid-base equilibrium (pH) potassium is basic for the excita

Risk of embolization, Systemic embolization occurs in 22 per cent to 50 per...

Systemic embolization occurs in 22 per cent to 50 per cent of cases of IE. Emboli often involve major arterial beds, including lungs, coronary arteries, spleen, bowel, and extremit

Define interaction of vitamin c with other vitamins, Define Interaction of ...

Define Interaction of Vitamin C with other vitamins? a. Ascorbic acid and other vitamins: Ascorbic acid synthesis is diminished in thiamin and riboflavin deficiency. Vitamin

How does phosphocreatine act in the muscle contraction, How does phosphocre...

How does phosphocreatine act in the muscle contraction and relaxation? Phosphocreatine is the main means of energy storage of the muscle cells. During relaxed periods ATP mo

Eczema, E c z e m a It is inflammatory reaction of epidermal cells...

E c z e m a It is inflammatory reaction of epidermal cells to the substances to which these cells are sensitized. Such substances may be present either in the external or

Speculate why stoma in the lower epidermis, Carbon dioxide needed for photo...

Carbon dioxide needed for photosynthesis enters the leaf via the stomata but water is also lost when these pores are open. Water is often limiting and to limit water loss through s

Ilustrate about corvous caurinus, When we watch animals in the wild, most o...

When we watch animals in the wild, most often we see them foraging for food. The foraging behaviour of animals has been a focus of behavioural studies for many decades. Natura

Endoplasm and ectoplasm, Normal 0 false false false EN-...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Golgi apparatus, GOLGI  APPARATUS It is a complex cyctoplasmic stru...

GOLGI  APPARATUS It is a complex cyctoplasmic structure made up of smooth membrane saccules or cisternae, a network of tubules with vessicles and vacuoles, which take part i

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