Types of embryosac monosporic, bisporic, tetrasporic , types of embryosac with its example

1. Plant Embryology:
Types of Embryo sac
Dr. Sonali Randive - Aherkar

2. TYPES OF EMBRYO SAC:
•Monosporic
•Bisporic
•Tetrasporic

3. WHAT IS MONOSPORIC EMBRYO SAC :
 It is a type of embryo sac in which Only one
megaspore out of the four megaspore take part in
the development of embryo sac.
 Polygonium
 Oenothera

4. POLYGONIUM:

5.  Polygonum type of embryo sac is eight nucleate.
 Nucleus of functional megaspore divide to form two
nuclei.
 One move towards micropyle & other to words
chalaza.
 It again undergoes nuclear division to form Tetra
nucleate stage.
 Nuclei in tetra nucleate stage again divide to form
eight nucleate stage.

6.  After eight nucleate stage the nuclear divisions
stops & nuclei moves to form the embryo sac.
 One, One nuclei each from micropyle & chalaza
come in the centre to form secondary nucleus.
 Three nuclei at micropyle functions as egg
apparatus in which middle nuclei functions as egg &
lateral two as synergids.
 Three nuclei at chalaza functions as antipodal cells.
 Found in Rosaceae, Rubiaceae, Rhamnaceae,
Astraceae, Casuarinaceae

7. OENOTHERA:

8.  This type of embryo sac is 4 nucleate.
 In this the functional megaspore at chalazal end
undergoes nuclear division.
 The megaspore divide to form bi nucleate stage but
both the nuclei move towards chalaza, there is no
nuclei at micropylar end.
 The calazal two nuclei undergoes further nuclear
division to form four nucleate stage.

9.  At four nucleate stage the nuclear division stops. And
forms the embryo sac.
 Out of the four nuclei at chlazal end one move toward
centre to act as a secondary nucleus.
 Three at chalazal end acts as egg apparatus Middle
functions as egg and two lateral synergids.
 Found in family onagraceae.

10. BISPORIC EMBRYO SAC :
 In this type both the nuclei which are formed at the
dyed stage are participated in formation of embryo
sac.
 Typically they are 8 nucleate.
 There are two types of Bisporic embryo sac
 Allium
 Endymion

11. ALLIUM:

12.  The functional megaspore forms dyad but the cell
plate is not formed so, both nuclei lie in same
megaspore & participate in formation of embryo sac.
The dyed cell at micropylar end become active &
chalazal become degenerate.
 The binucleate stage undergoes nuclear division to
form tetra nucleate stage. The Four nucleate stage
again undergoes division to form eight nucleate
stage.
 These eight nuclei arranged to form embryo sac.

13.  Three nuclei at micropyle functions as egg
apparatus.
 Middel two functions as secondary nucleus.
 Three at the chalazal end functions as antipodal
cells.
 Found in Allium,
Liliaceae,Amaryllidaceae,Orchidaceae, Alismaceae.

14. ENDYMION:

15.  The dyed cell at micropylar end become active &
chalazal become degenerate.
 The binucleate stage undergoes nuclear division to
form tetra nucleate stage. The Four nucleate stage
again undergoes division to form eight nucleate
stage.
 These eight nuclei arranged to form embryo sac.
 Three nuclei at micropyle functions as egg
apparatus.

16.  Middel two functions as secondary nucleus.
 Three at the chalazal end functions as antipodal
cells.
 Found in Endymion hispanicus, Polygonum

17. TETRASPORIC:
 In tetrasporic embryo sac Four embryo sacs
participate in development of embryo sac.
 Usually they are 16 nucleate.
 Pepromea
 Penaea
 Drusa
 Chrysanthemum
 Fritillaria
 Plumbagella
 Plumbago
 Adoxa

18. PEPROMEA:

19.  In this type the functional megaspore undergoes
nuclear division to form binucleate stage.
 Binucleate stage undergoes further nuclear division &
arranged peripherally.
 Tetra nucleate stage again undergoes division to form
8 nucleate stage.
 8 nucleate stage nuclei again undergoes division to
form 16 nucleate stage at this stage nuclear divisions
stops.
 16 nuclei arranged to form embryo sac.

20.  8 nuclei comes in the centre to form secondary
nucleus.
 2 nuclei at micropyle end functions as one egg & 1
synergids.
 Remaining 6 nuclei arranged peripherally.

21. PENEA TYPE:

22.  This type is very much similar to Pepromea type of
embryo sac.
 It shows presence of 16 nucleate stage.
 Only differ in arrangement of embryo sac.
 16 nuclei lie in four diffrent corners crosswise.
 One at each end of embryo sac & two at sides.
 One, one nuclei from each corner comes in the
centre to form secondary nucleus. Micropyle one
nuclei functions as an egg.
 This type is found in malpighinaceae.

23. DRUSA:

24. DRUSA:
 In this type 16 nucleate embryo sac is observed.
 After division three nuclei move towards basal end
of embryo sac, one remain at micropylar end.
 Successive divisions results in to four micropylar
nuclei & 12 antipodal cells.
 Four nuclei give rise to egg apparatus.
 This type is recorded in Rubia, Ulmus, Mallotus

25. CHRYSANTHEMUM:

26.  This type of embryo sac shows presence of 6, 9,10 or
12 nuclei.
 Shows presence of 1+2+1 arrangement, i.e 2 nuclei at
both sides of embryo sac & 2 in middle.
 Some times middle two nuclei fuse & functions as
single.
 Thses single nuclei again undergoes division up to 12
nucleate stage.
 3 nuclei at micropyle functions as egg apparatus.
 Middle 3 functions as secondary nucleus.
 Remaining 6 functions as antipodal cells at the calazal
end.

27. FRITILLARIA :

28.  After division of functional megaspore two times
fore nuclei are formed, out of that 3 comes to
chalazal end & fuse to form a single & nuclei at
micropylar end get divides to form haploid nuclei.
 After further division it can form 8 nuclei.
 4 chalazal nuclei are triploid, four micropyle haploid.
 One nuclei from both sides come in centre to form
sec. Nucleus which shows presence of one haploid
& one triploid nuclei. Reported in Lilium, piper ,
Tamarix etc.

29. PLUBAGELLA:

30.  This type of embryo sac reported in Plumbagella
micrantha.
 Here the 4 megaspores take 1+3 arrangement, 3
nuclei at chalazal end & at micropyle.
 These three nuclei at calazal end get fuses to form
one.
 Now this binucleate stage divides to form tetra
nucleate stage after this stage there is no further
division.
 1 nuclei at micropylar end two nuclei in the centre
& 1 triploid nuclei at the chalazal end.

31. PLUMBAGO:

32.  This type reported in Plumbago capensis.
 4 megaspore nuclei arranged crosswise & divide to
form 8 nuclei arranged in 4 pairs.
 1 nuclei cut off to form egg cell, One nuclei from
each pair comes in centre to form sec. nucleus &
fuse to form tetraploid endosperm nucleus.
 Remaining nuclei degenerate.

33. ADOXA:

34. ADOXA:
 This type of embryo sac found in Adoxa
moschatellina.
 In this type 4 megaspores divide to form 8 nuclei &
arranged like normal embryo sac.

35. Type of embryo sac Nuclei
Polygonum 8
Oenothera 4
Allium 8
Endymion 8
Pepromea 16
Penea 16
Drusa 16
Chrysanthemum 6,8,9,10,12
Fritillaria 8
Plumbagella 4
Plumbago 8
Adoxa 8