Polygonum type - monosporic embryo sacs, Biology

Assignment Help:

Polygonum Type - Monosporic Embryo Sacs

The embryo sac is formed from the chalazal megaspore in the tetrad and is eight-nucleate. The development of the embryo sac begins with elongation of the functional megaspore. Initially, the megaspore cytoplasm is non-vacuolated but later small vacuoles appear which fuse to form a large vacuole. The spindle of the nuclear division in the megaspore is oriented along the long axis of the cell. Wall is not formed after the nucleus divides.

A large central vacuole appears between the two daughter nuclei. It expands and pushes the nuclei towards the opposite poles of the cell. Both the nuclei divide to form four nuclei, two at each pole. By a further division an eight nucleate condition is reached. This is followed by cellular organisation of the embryo sac. Out of the four nuclei at the micropylar end of the sac, three organize into egg apparatus and the fourth is left free in the cytoplasm of the central cell as the upper polar nucleus. Similarly, three nuclei of the chalazal quartet form three antipodal cells; the fourth one functions as the lower polar nucleus. Eventually, the latter comes to lie close to the upper polar nucleus.


Related Discussions:- Polygonum type - monosporic embryo sacs

Digestion in coakroach, Awhat is the function of malpigrium tubulessk quest...

Awhat is the function of malpigrium tubulessk question #Minimum 100 words accepted#

Explain about regenerative therapy, Explain about Regenerative therapy   ...

Explain about Regenerative therapy   Is also used to achieve the above objectives but with the ultimate goal of regeneration of lost bone tissue.

Construct cdna samples, Once you have identified a few relevant mRNA specie...

Once you have identified a few relevant mRNA species, you wish to more closely examine their messages by sequencing. You do not have the time to search the genome and isolate the D

Use of syphilis in pregnancy, Syphilis in Pregnancy Syphilis in pregna...

Syphilis in Pregnancy Syphilis in pregnant women should be treated with penicillin in doses appropriate to the stage of the disease. When pregnant women with syphilis are alle

What is oxidation and reduction, What is Oxidation and Reduction? Oxid...

What is Oxidation and Reduction? Oxidation and Reduction :   Most people are familiar with oxidation as it pertains to the rusting of metals. Oxygen grabs electrons from iron

Hazard, Hazards Is an event whether natural or man-made that has potential ...

Hazards Is an event whether natural or man-made that has potential for causing injury, loss of life and damage to the property or the environment. It can be grouped into two broad

What are the major components of the cytoskeleton, Q. What are the major co...

Q. What are the major components of the cytoskeleton? The cytoskeleton is a network of very small filaments and tubules distributed throughout the cytoplasm of eukaryotic cells

Characteristics of hormones, CHARACTERISTIC S OF HORMONES - (1)      T...

CHARACTERISTIC S OF HORMONES - (1)      They are regulatory chemicals that control and coordinate functions of different body organs. (2)      Hormones are formed by ductle

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