Female gametophyte, Biology

Assignment Help:

Female Gametophyte

The development of a female gametophyte is initiated with the enlargement of one of the megaspores (usually the one close to the chalaza in a linear tetrad) followed by three mitotic divisions. Thus, the female gametophyte, also called the embryo sac is almost always a 7-celled or 8-nucleate structure. The eight nuclei thus formed organize into the egg apparatus, central cell with two polar nuclei and three antipodal cells. This mode of embryo sac development occurs in the majority of flowering plants.

There are variations from this mode of female gametophyte development. In order to visualize these deviations let us recall the formation of megaspore tetrad. Out of the four megaspores, three degenerate and only one participates in the formation of embryo sac. This mode of development of female gametophyte is known as the monosporic type. In some plants, two megaspores out of four participate. For example, if after meiosis, the lower or the upper dyad produces the embryo sac and the other degenerates, the development is termed bisporic. Sometimes, cell plate formation does not occur after any of the meiotic divisions and all the four megaspore nuclei contribute to embryo sac formation. 'This is called tetrasporic type of development. Depending upon the orientation and subsequent behavior of the megaspore nuclei and their derivatives, the tetrasporic gametophyte may be of several types.


Related Discussions:- Female gametophyte

Our healthi diet, in what form is most carbohydrates is taken in normal die...

in what form is most carbohydrates is taken in normal diet

Response to flooding, Response to Flooding Prolonged flooding or water...

Response to Flooding Prolonged flooding or water-logging creates anaerobic conditions for the sub-surface parts of the plant and synthesis of alcohol dehydrogenase (ADH) helps

Reproduction, what is the difference between anaisogyami & oogyami?

what is the difference between anaisogyami & oogyami?

Metamorphosis, What type of metamorphosis do spongs go through is it reteog...

What type of metamorphosis do spongs go through is it reteogressive?

Explain clinical dietetics and diet therapy, Explain Clinical dietetics and...

Explain Clinical dietetics and Diet therapy Clinical dietetics  :  The application of  dietetics  in a hospital or health care institutional  setting. Diet therapy  :

Explain the results of coarctation of aorta, Explain the Results of Coarcta...

Explain the Results of Coarctation of Aorta? Early hospital death in isolated coarctation is around 2 to 10 per cent. In many reports, mortality for older babies approaches 0.

Cell physiology, why is epidermis peeledsuggest why a marine amoeba does no...

why is epidermis peeledsuggest why a marine amoeba does not have a contractile vacuole

Define the functions of vitamin e, Define the Functions of Vitamin E? V...

Define the Functions of Vitamin E? Vitamin E is the major lipid-soluble antioxidant in the cell antioxidant defence system and is exclusively obtained from the diet. The main r

Pre-embryonic development, Pre-Embryonic Development We had said in t...

Pre-Embryonic Development We had said in the starting of the unit that prenatal development can be divided into two phases, embryonic and foetal. The embryonic phase of devel

Chest x-ray, Increase in cardio-thoracic ratio is a relatively specific ind...

Increase in cardio-thoracic ratio is a relatively specific indicator of left ventricular end-diastolic volume. Left atrial enlargement is seen as double density shadow, lifting up

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