Structure & Types of ovule

The ovule is a multicellular oval-shaped structure which originates from the placenta and lies inside the chamber of the ovary.
Gymnosperms – Naked
Angiosperms – Integumented
A fully mature ovule consists of the stalk or funicle and the body.
The body of the ovule shows two ends –
Basal end - Chalaza &
Upper end - Micropylar end
Hilum - The point of attachment of the funicle with the body
Body of the ovule
Integuments
Nucellus &
Embryo Sac

Integuments
Protecting layers
Unitegmic or bitegmic
Micropyle-small opening at the apex of the integument, Entrance for Pollen tube.
Nucellus
Parenchymatous, nourishing
Embryo sac/female gametophyte - oval, at the micropylar end; contains egg apparatus.
Egg Apparatus
Egg cell or ovum – Central, forms the female gamete
Synergids - nonfunctional, short-lived
Antipodal cells – 3, non functional, short-lived
Nucleus – 2, Polar nuclei, one fuses with male gamete and grows into the endosperm of the seed.
Types of Ovule
Orthotropous
Anatropous
Hemianotropous
Campylotropous
Amphitropous
Circinotropous
Dr. T. Annie Sheron
Annie Sheron
Kakatiya Government College

1. Structure & types of
Megasporangium
(Ovule)

Dr. T. Annie Sheron
Asst. Professor of Botany
Hanamkonda, Telangana

2. Structure

Stigma

Anther,
| Style }Carpel
Stamen

Ovary

Filament

Nucellus

2 polar nuclei
(n)

‘on

Integuments

Femal
gamet

ame Courtesy: http//leavingbio.net/structure-tunctions-flowers/

The ovule is a multicellular oval-shaped structure whi
originates from the placenta and lies inside the chamber of tl
ovary.

3. y Gymnosperms — Naked

Chalaza

y Angiosperms — Integumented
Antipodals

Y A fully mature ovule consists of

Ani Secondary Nucl
the stalk or funicle and the body. BES N
Y The body of the ovule shows two 5 Enge
ends — LL Inner Integumer

— Basal end - Chalaza &

Funicle
— Upper end - Micropylar end
y Hilum - The point of attachment of
age . Structure of ovule
the funicle with the body Demon

Placenta

4. y Body of the ovule
— Integuments

Chalaza

— Nucellus & Antipodals
E Embryo Sac — Secondary Nucl
JB! Embryo sac
Integuments \ A ae
yf E > y Outer Integume
Protecting layers Inner Integumer

Y Unitegmic or bitegmic
Y Micropyle-small opening at the
apex of the integument, Entrance
for Pollen tube.
Nucellus
Parenchymatous, nourishing
Embryo sac/female gametophyte - oval, at the micropylar end:
contains egg apparatus.

Funicle

Placenta

Structure of ovule

Courtesy: www.topperlea ring com

5. Egg apparatus

y Egg cell or ovum — Central,
forms the female gamete

y Synergids - nonfunctional,
short-lived

y Antipodal cells — 3, non
functional, short-lived

Y Nucleus — 2, Polar nuclei, one

fuses with male gamete and

grows into the endosperm of the

seed.

Chalazal end

Polar nuc

Central
cell

Micropylar end

6. Types of Ovule

(a) Orthotropous (b) Anatropous (c) Hemianatropous

(d) Campylotropous (e) Amphitropous (f) Circinotropous

Courtesy: https: //wwww. brainkartcom/

7. Orthotropous

Micropyle

Integuments
Embryo sac

Nucellus

Chalaza
Funicle

Simplest and primitive
Micropyle, chalaza and funiculus
lie in one vertical plane.

x: Piperaceae and Polygonaceae.

Anatropous

Y Most common

¥Body of the ovule complet
inverted so that micropyle
close to the funicle

Ex: Asteraceae.

8. Hemianatropous

Chalaza Nucellus Embryo sac

Body of the ovule is
dlaced transversely and at
ight angles to the funicle.
: Primulaceae.

Campylotrop«

Integuments 5 >
Embryo Mi S Re

sac MON Jy

Micropyle Chalssy
Funicle

Nucellus

y Body of the ovule at the micropylar «
is curved and more or less bean shape:

YEmbryo sac slightly curved. hilt
micropyle and chalaza are adjacent
one another, with the micropyle orien
towards the placenta.

VEx: Leguminosae.

9. Amphitropous

Ri

|

Distance between hilum and

chalaza is less
Curvature of the ovule leads to

horse-shoe shaped nucellus.

x: Alismataceae, Butamaceae

Circinotropous

Circinotropous
Ovule

¥Funiculus is very long and
surrounds the ovule
vEx: Cactaceae.