Question

describe development of female gametophyte in cycas

Answer 1

Answer

• The functional megaspore is the first cell of the female gametophyte.

• The haploid nucleus of the megaspore divides by three repeated mitotic division.

• It tend to form an eight nucleate female gametophyte or embryo sac.

• After the first division the two daughter nuclei moves to the opposite poles.

• The nucleus at each pole divides into two and then in to four nuclei.

• At this stage there are four daughter nuclei at each pole.

• Cell membrane and cell wall develops around all the nuclei, except the two at the centre.

• The three cells at the micropylar end of the embryo sac develops into an egg apparatus.

• The central large cell of the egg apparatus is the female gamete or egg cell and the two either sides are synergids.