The Process of Megasporangenesis in Angiosperms : Biology Blog

                                        Megasprogenesis 

• The formation of megaspore mother cells from megaspore mother cells is called megasporogenesis. 
  
  
• This process occurs inside the nucellus of developing ovule of angiosperms.
  
  
• It is surrounded by a layer known as the epidermis.
  
  
• Below the epidermis, there is a layer known as hypodermis.
  
  
• One cell of hypodermic divide and grow in a bigger size which is known as archesporial cells.
                                        
  
  
• These archesporial cells divide periclinal to form an outer parietal layer and inner sporogenous cells.
  
  
• These sporogenous cells function as megaspore mother cells (MMC).
  
  
• These cells divide meiotically and form four haploid tetrad cells. Out of which three degenerate and only one remain is functional.
  
  
• Only now functional megaspore develops into the female gametophyte.
  
  
• Now, the nucleus of the functional megaspore divides mitotically to form two nuclei.
  
  
• These two nuclei now move to the opposite poles and start dividing mitotically and form four nuclei.
  
  
• These four nuclei divide further and form a total of 8 nucleates of the Embry Sac. 
• One nucleus from the chalazal end and one nucleus from the micropylar end moves to the center and fuse to form secondary nuclei or central cells and in this way, they form 7 celled 8nucleate embryo sac.  
  
  
• The three nuclei at the base are known as antipodal cells.
  
  
• The two nuclei at the micropylar end are known as synergid cells and one cell is known as egg cells. 
  
  
• At the base of the synergid cells, some finger-like projection is present which is known as filiform apparatus help in pollen fertilization.  
  
  

you can also visit double fertilization by clicking on the following link -
https://bioisnotdifficult.blogspot.com/2018/11/double-fertilisation-in-hindi-biology.html