Explain the structure of megasporangium.

Explanation

Structure of Mature Anatropous Ovule: Ovule represents the megasporangium. Anatropous ovule is an inverted ovule (due to 180@turn) in which funcile and microphyle lie close to each other.
It slows the following parts .
(1) Funicle :: It is the stalk of the which ovule is attached to placenta in the ovary.
(2) Hillum : It is the region at which ovule is attached to the funicle .
(3) Raphae : It is the extended part of the funcile beyond the hilum.
(4) Chalaza : It is the basal part of the ovule at which integuments orginate.
(5) Interguments : These are outer protective covering of the ovule.These completely enclose the nucellus except for the region at the apex called micophyle.
Nucellus : It is the female gametophyte present in the nucleus towards the microphylar end.It consists of three antipodal cells towards chalazal end appartatus towards the micopylar end Egg cell and two lateral synegrid cells .
(7) Embryosac: It is the female gametophyte present in the nucleus towards the micropylar end. It consists of three antipodal cells towards chalazal end, secondary nucleus at the centre adn egg, apparatus towards the microphlar end ,Egg apparatus consists of a centeral eg cell and two lateral synergid cells.