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what is polygonum type of embryo sac?? plzz xplain in details..

The normal type of embryo sac development has been studied in Polygonum by Strasburger. Since this embryo sac develops from one megaspore, that is why this is monosporic embryo sac. It develops from chalazal functional megaspore (4th from micropyle). Nucleus of functional megaspore divides by three mitotic divisions to form 8 nuclei, out of which

(i) Three of them get organised as cells at micropylar end forming egg apparatus. One is egg cell (n) and two are synergids (n) or co-operative cells.

(ii) Three cells at chalazal end form antipodals (n) or vegetative cells of female gametophyte.

(iii) Two nuclei (one from each pole) in the centre are called polar nuclei (n)

As the embryo sac matures, these polar nuclei get fused to form a secondary nucleus (2n) or definitive nucleus.

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The normal type of embryo sac development has been studied in Polygonum by Strasburger. Since this embryo sac develops from one megaspore, that is why this is monosporic embryo sac. It develops from chalazal functional megaspore (4th from micropyle). Nucleus of functional megaspore divides by three mitotic divisions to form 8 nuclei, out of which

(i) Three of them get organised as cells at micropylar end forming egg apparatus. One is egg cell (n) and two are synergids (n) or co-operative cells.

(ii) Three cells at chalazal end form antipodals (n) or vegetative cells of female gametophyte.

(iii) Two nuclei (one from each pole) in the centre are called polar nuclei (n)

As the embryo sac matures, these polar nuclei get fused to form a secondary nucleus (2n) or definitive nucleus.

  • -2

The normal type of embryo sac development has been studied in Polygonum by Strasburger. Since this embryo sac develops from one megaspore, that is why this is monosporic embryo sac. It develops from chalazal functional megaspore (4th from micropyle). Nucleus of functional megaspore divides by three mitotic divisions to form 8 nuclei, out of which

(i) Three of them get organised as cells at micropylar end forming egg apparatus. One is egg cell (n) and two are synergids (n) or co-operative cells.

(ii) Three cells at chalazal end form antipodals (n) or vegetative cells of female gametophyte.

(iii) Two nuclei (one from each pole) in the centre are called polar nuclei (n)

As the embryo sac matures, these polar nuclei get fused to form a secondary nucleus (2n) or definitive nucleus.

  • 2
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