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Draw a well-labelled diagram of a mature ovule, showing its internal structure.

Ans. Parts of Angiospermic Ovule: The ovule is called megasporangium. It is a small structure attached to placenta by a stalk named funicle. At hilum, the body of ovule is fused to funicle. 

Each ovule possesses one or two integuments which enclose ovule except the micropyle.

Chalaza is the basal part of an ovule. The nucleus encloses a mass of cells. Emrbyo sac is 7 celled but 8 nucleate lies in the ovule. It is called female gameto phyte.

(b) Mature female gametophyte :----

At 8 nucleate stage of embryo sac, the
cell walls are laid down. Six of 8 nuclei are surrounded by cell walls and organized into the cells. The remaining 2 nuclei in 
the centre of emrbyo sac are polar nuclei.

 They lie below egg apparatus in the big central cell. Three cells at micropylar end form egg apparatus. 

It has 2 synergids and one egg cell. Three other cells at chalzal end form antipodals. The big central cell has 2 nuclei. So mature 8 nucleate embryo sac is 7 celled.

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