2. CONTENT
TYPES OF OVULE
MEGASPOROGENESIS
DEVELOPMENT OF FEMALE GAMETOPHYTE
(EMBRYO SAC )
3. OVULE
The plant ovule is a part of female reproductive
organ
It is that part of plant reproductive cells are
made and kept and these cells develop into
seeds after fertilisation
These seeds later ripens and turns into an adult
plant
5. FUNICLE ;-
It is a stalk shape structure
The site where funicle is attached with ovary
is called hilum
It is attached with placenta
It connect ovule with ovary with ovary by
placenta
INTEGUMENT;
It is covering of ovule
It forms seed coat
6. NUCELLUS ;
This is the largest part of ovule
It contain embryo sac and nutritive tissue
It is found between embryo sac and inetgument
It is made up of parenchymatous cells where food is
stored
EMBRYO SAC;
It is the main part of ovule where fertilisation occurs
MICROPHYLE ;
The site where inetgument is absent
It’s a small pore from this pollen tubee enter in
embyo sac
7. CHALAZA ;
It is opposite pole of micropyle
TYPES OF OVULE
There are six types of ovules based on there
shapes ;
1 atropous
2 anatropous
3 hemianatropus
4camplyotropous
5 amphitropous
6 circinotropous
8. ATROPOUS;
. In this funicle ,chalaza,and micropyle are situated on one axis
example ; black pepper
9. HEMI ANATROPOUS ;
. the ovules takes the shape of right angle in the relation to its funicle
. It looks like the ovule is lying on its side
example; rananculus
10. ANATROPOUS ;
. It is inverted
.micropyle lies close to hilum
example ;82% angiosperm
13. Circinotropous ;
. The shape of it is the most distict of them all
.the funicle is so long that it create a full circle around the ovule and its
micropyle ultimately points upward
example ; cactaceae family
14. Megasporogenesis
Formation of megaspore by megaspore mother cell
(MMC)is called megasporogenesis
Formation of megaspore ;
during development of ovule a cell from nucellus
become large and cytoplasm become dense and this
cell is called archaesporal cell
Now this cell divides and form two cells
1 primary wall cell
2 primary megasporogenesis pr megaspore mother
cell (2n)
15. Megaspore mother cell divide meiotically and form 4
megaspore and this strucutre is called megaspore
tetrad
3 megaspore are inactive which are present towards
micropyle pole
active megaspore is located on chalaza pole
inactive megaspore degenrate after some time and
only 1 megaspore remains
18. Developed female gametophtye is called embryo sac
In most of the angiosperms embryo sac is called 7
celled and 8 nucleated structure 3 cells which are
located on chalaza pole are called antipodal cell
A binucleated cell which is located in the centre of
embryo sac is called central cell
Central cell form a triploid endosperm with the fusion
of male nucleus
A group of 3 cell [ 2 synergids +1 egg cell ] are
located on micropyle is called egg apparatus
19. DEVELOPEMENT OF FEMALE GAMETOPHYTE;
In this process megaspore cell become large
Now nucellus of the cell divides by mitosis
now these nucleus move towards their pole . Now 1
nucleus is situated at chalaza pole and other
nucleus is situated in micropyle pole
Now this nucleus divides continueously 2 times by
mitosis
Now every pole have 4 nucleus after this 1 nucleus
from each pole move towards middle plate
after this all incident a 7 celled and 8 nucleated
structure is formed which is called female
gametophyte