Egg - synergids, Biology

Assignment Help:

Egg - Synergids

The three cells of the egg apparatus are arranged in triangular fashion with the egg sharing a common wall with the two synergids and the central cell. In the egg the wall is thicker at the micropylar end and is absent at the chalazal end. At this end the lateral walls of the egg cell appear to join the central cell wall. The egg cell wall is traversed by plasmodesmata on the sides of the two synergids and the central cell but not at its outer face. The egg cell becomes highly polarized early in its development. Polarity is expressed by the aggregation of cytoplasmic elements at the chalazal end of the cell. The micropylar end of the cell is occupied by a large vacuole. Thus, the distribution of the vacuole and cytoplasm in the egg cell is just the opposite of that in the synergids.

The ultra structure of the egg cytoplasm indicates that it is inactive. The mitochondria show only a few cristae. But for Zea mays, dictyosomes are either absent (Epidendrum) or are only a few in numbers. Where present, the dictyosomes exhibit an inactive state. Plastids are present in the egg; they often contain a striking difference from the male gametes. The egg cytoplasm is rich in ribosomes. In Plumbago capensis where the embryo sac lacks synergids. However many finger- like wall projections arise at the micropylar end of the egg cell. They resemble the filiform apparatus of the synergids. In this plant the egg cell seems to have taken over the role of synergids in addition to its own gametic function.


Related Discussions:- Egg - synergids

Explain about the duration of exercise for diabetics patient, Explain about...

Explain about the duration of exercise for diabetics patient After selecting an exercise, it is very important to know the vigorous nature, duration and timings of the exercise

Define the management of epileptic patients, Define the Management of Epile...

Define the Management of Epileptic Patients? The primary treatment of epilepsy is anticonvulsant drugs. The focus of nutritional management is a diet, which is appropriate for

Explain the bunsen burner, Explain the Bunsen Burner? It is a type of g...

Explain the Bunsen Burner? It is a type of gas burner that gives very hot flame by allowing air to enter at the base and mix with the gas. It is used - (a) For sterilizing i

Detailed explanation of effects of air pollution, On living organism  ...

On living organism           Air pollution causes following effects on living organism: (a)   Effects on humans: 1.      Carbon monoxide reduces the oxygen carrying cap

Define about the geriatric nutrition, Define about the Geriatric Nutrition?...

Define about the Geriatric Nutrition? Aging has been defined as "a series of time related process that ultimately brings life to a close." Persons of 60 years of age and older

Applications of oracle clinical in pharmaceutical industries, Question 1: ...

Question 1: Write the applications of Oracle clinical in Pharmaceutical industries Explain what is "Oracle clinical" Explain different application of oracle clinical

How can triglycerides be decreased, Q. How can triglycerides be decreased? ...

Q. How can triglycerides be decreased? Triglycerides could be decreased by: - limiting foods high in fats - decreasing sugar and sugar containing foods (carbonated bevera

Avian tuberculosis, Avian tuberculosis The infection in poultry usuall...

Avian tuberculosis The infection in poultry usually occurs from ingestion of contaminated food and water. The lesions develop in spleen, liver and intestines; less frequently

Can you illustrate compensation point, Q. What is compensation point? What ...

Q. What is compensation point? What is the inference of the compensation point for the plant growth? The photic compensation point is the photic energy intensity under which ae

Can you explain the anoxia, Q. What is the anoxia? Anoxia is a situatio...

Q. What is the anoxia? Anoxia is a situation in which there is no available oxygen in the cell without oxygen the respiratory chain stops there is no ATP production the cell do

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