embriologi tumbuhan_materi 2

8/16/2019 Embriologi Tumbuhan_materi 2

http://slidepdf.com/reader/full/embriologi-tumbuhanmateri-2 1/21

Embriologi Tumbuhan (BI406; 2 SKS)Materi 3 dan 4

Struktur Organ Reproduksi

Angio!ermae

MegasporangiumMegasporogenesis

Megagametogenesis

An overview



Struktur Bunga

"#ulum$ megasporangium with its

protective coats, the

integuments

%umber o& integumen$1. Unitegmic ovule

2. Bitegmic ovule

Angiosperms



Five main types of ovuleFive main types of ovule

Classification based on the position ofmicropyle with respect to funiculus



Relationship among the five typesRelationship among the five types

of ovulumof ovulum



Stages in ovule developmentStages in ovule development

A. Ovule arises as a small mound of homogenous tissue on the placenta

B. Integumen arise close to the base of this tissue which forms the

nucellusC. !. "ith the differentiation of integuments, the ovule begins to curve

#. $he final shape of ovule is assumed b% the megaspore tetrad stage.



NucellusNucellus

1. &ucellus reprecent the wall of megasporangium

2. Archesporium 'megaspore mother cell( differentiates immediatel% below

the nucellar epidermis). !epend on the thic*ening of nucellus, ovule classified into tenuinucellate,

crassinucellate, and pseudocrassinucellate.

Tenuinu'ellate o#ule


http://slidepdf.com/reader/full/embriologi-tumbuhanmateri-2 7/21NucellusNucellus

rainu'ellate o#ule

eudo*'rainu'ellate o#ule



Megasporogenesis andMegasporogenesis and

GametogenesisGametogenesis


http://slidepdf.com/reader/full/embriologi-tumbuhanmateri-2 10/21Stage of MegasporogenesisStage of Megasporogenesis


http://slidepdf.com/reader/full/embriologi-tumbuhanmateri-2 11/21Embryo sac (Development)Embryo sac (Development)

The development of embryo sac begin withelongation of the functional megaspora,

which could be the calazal end or micropylarend of the tetrad (usually the calazal one)The elongation is largely in the micropyle-

calazal axis

The Megaspore is initially has no vacuole,the large vacuole appear later as a result ofsmall vacuoles fusionirst nuclear division in the functional

megaspore is oriented along the axis of thecell!



+icrop%lar end



The two daughter nuclei are pushed towardopposite poles (fig! ")

#oth nuclei divide twice forming four nuclei at eachpole (fig! #, C)

$hile the cell (megaspore) undergoing appreciableelongation, assuming a sac li%e appearance, thethree nuclei at the micropylar end organize into

egg apparatus and one nuclei is left free in thecytoplasm as the upper polar nucleus! "t the sametime, three nuclei of the calazal pole form threeantipodal cells and the fourth one function as the

lower polar nucleus (fig! &, ')The upper and the lower polar nucleus come to lie

close each other (fig! ')


http://slidepdf.com/reader/full/embriologi-tumbuhanmateri-2 14/21Mature Embryo SacMature Embryo Sac

Synergid

1. Karakteristik

&ua sel yang berdampingan dengan sel telurdindingnya tida% sempurna memili%i aparatus filiform(a mass of finger-li%e proection of the wall intocytoplasm sitoplasmanya terpolarisasi (leta% va%uolalebih %earah %alaza)

2. Fungsi directing of pollen tube growth forms a seat for pollentube discharge in the embryo sac absorption andtransportation of materials from nucellus into embryosac



Sel elur

*!Memili%i stru%tur dinding sel yang relatif samadengan synergid dan central cell (polar cell)

+!&inding di daerah mi%ropil lebih tebaldibanding%an daerah %alaza

!&alam per%embangannya, sel mengalamipolarisasi sebagai a%ibat teradinya agregasi

elemen-elemen sitoplasma pada uung %alaza!.a%uola menempati uung mi%ropil (%ebali%an dari

sinergid)

/!0itoplasmanya %aya dengan ribosom



!ntipodal cells

*!1ara%ternya sangat bervariasi

+!#iasanya mengalami degenerasisebelum atau segera setelah fertilisasiteradi

!2ada beberapa species tumbuhanbersifat persistent (ada hubungannyadengan nutritive role bagi %antung

embrio)!3n many plant show a haustorialbehaviour



"entral cells#$olar cells

*!The largest cell of the embryo sac+!Mother cell of the endosperm

!The nuclei (polar nuclei) are verylarge

!The nuclei fuse before or duringdouble fertilization


http://slidepdf.com/reader/full/embriologi-tumbuhanmateri-2 18/21ipe %antung Embrioipe %antung Embrio

! i b e d a * a n

b e r d a s a r * a n b a

n % a * n % a m e g a s p o r a % a n g

t e r l i b a t d a l a

m m

e g a g a m e t o

g e n e s i s , p e m b e n t u * a n

* a n t u n g e m

b r i o



Monosporic

The embryo sac is derived from onlyone magaspore

1.Polygonum type4 the embryo sac isformed by chalazal megaspore with

three time mitosis

2.Oenothera type4 the embryo sac isformed bay micropylar megaspore

with two time mitosis



&isporic- The embryo sac is derived from two magaspore- 2embelahan meiosis pertama berlangsung

sempurna, tetapi hanya salah satu sel ana%yang mela%u%an meiosis %edua! 0atu sellainnya degenerasi!

- 1edua megaspore mela%u%an pembelahanmitosis dua %ali membentu% %antung embriodengan 5 inti

1. Alium type4 the embryo sac is derived fromchalazal dyad cell

2.Endymion type4 the embryo sac is derived frommicropylar dyad cell



etrasporic

- The embryo sac is derived from four magaspore

- Teradi %arena pembelahan meiosis 3 dan 33 tida%dii%uti dengan pembentu%an dinding sel, shg intisel hasil meiosis berada dalam satu sel(coenomegaspore)

-

1eempat inti dalam coenomegaspore terlibatdalam pembentu%a %antung embrio

- 6uclear behaviour is 7uite variable (see slide *5),depend on the arrangement of the four nuclei(*8*8*8* in Paperomia, Penaea, and Plumbago

type *8 in Drusa, Fritilaria, Plumbagella type+8+ in Adoxa type)

embriologi tumbuhan_materi 2

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