This document summarizes the structure and development of the female gametophyte in flowering plants. It notes that the female gametophyte, also called the embryo sac, develops from a megaspore mother cell into a usually seven-celled, eight-nucleate structure consisting of three antipodal cells, one central cell with two polar nuclei, two synergid cells, and one egg cell. Megasporogenesis involves meiotic divisions of the megaspore mother cell to form a linear tetrad of megaspores, with one functional megaspore developing into the embryo sac through mitotic divisions that result in the characteristic cell types and nuclei.

1. FEMALE GAMETOPHYTE
PRESENTED BY
LOGANATHAN
I M.SC BOTANY
GOVT. ARTS COLLEGE - CBE

2. INTRODUCTION
 A gametophyte is a stage in
the life cycle of plants and
algae that undergo
alternation of generations.
 The gametophyte is the
sexual phase in the life
cycle of plants and algae.
 Cell division of the zygote
results in a new diploid
multicellular organism, the
second stage in the life cycle
known as the sporophyte,
the function of which is to
produce haploid spores by
meiosis.

3. STRUCTURE OF FEMALE
GAMETOPHYTE
 The female gametophyte
is also called the embryo
sac.
 In angiosperms it mostly
develops as a seven
celled, eight-nucleate
structure.
 It consists of three
antipodal cells, one central
cell, two synergid cells,
and one egg cell mostly.

4. STRUCTURE OF FEMALE
GAMETOPHYTE
 It generally contain
antipodal cells at chalazal
ends, an egg cell and two
synergids at microplyar
ends, and a center
containing two polar
nuclei.
 Embryo sec is expect the
center binucleate cell.
 The process of formation
of embryo sac is known as
megasporogenesis.

5. DEVELOPMENTOFFEMALEGAMETOPHYTE
The female gametophyte first arise as a
tiny protuberance from the placenta, in the
cavity of the overy.
As it mature,the ovule consists of a
nutritive cellular mass known as nucellus,
protected by two integuments, and
attached to the placenta by a funiculus.
Even at an early stage, one cell becomes
evident in the nucellus, which is known as
the megaspore mother cell(MMC).

6. DEVELOPMENTOFFEMALEGAMETOPHYTE
MMC is diploid (2n)
The MMC then increases in size, and
divides twice (meiotically) to from 4
megaspore as ‘linear tetrad’
The first division is a reduction division
The resultant megaspores are haploid (n)
Out of the four megaspores, three
degenerate, forming caps, while one
remains functional.

7. DEVELOPMENTOFFEMALEGAMETOPHYTE
This functionl megaspore is haploid (n)
The functional megaspore, then grows
rapidally, by absorbing nutrition from nucellus,
and forms the embryo sac.
The process of formation of embryo sac is
known as megasporogenesis.
The embryo sac consists of one nucleus.
The nucleus divided into two daughter nuclei,
which move towards the poles.
The pole of the embryo sac, closer to the
chalaza, is the chalazal end,and the one
closer to the microphyle is the micropylar end.

8. DEVELOPMENTOFFEMALEGAMETOPHYTE
 Each daughter nuclei divides again, and result in
four nuclei.
 Each nuclei divides again, for the last time, and
result in eight nuclei.
 One nuclei from each end, come to the centre,
and fuse to from a diploid secondary nucleus.
 The nuclei at the chalazal end, get surronded by
cytoplasm, and form three distinct, haploid,
antipodal cells.
 Similarly, the nuclei at the micropylar end, form
the egg apparatus, consisting of tow haploid
synergids on either side of a large, central,
haploid egg cell.

9. DEVELOPMENT OF FEMALE GAMETOPHYTE

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