Download Animal Development

Animal
Growth and
Development
What is the
Different between
Growth and
Development??
Animal Development
• Introduction
to animal development
Development requires both cell growth and cell

differentiation (different cells express different
genes)
How are new organisms produced?
Fertilization
• In mammals, sperm travel from the
vagina to the fallopian tube
• Fertilization takes place in the
fallopian tube to form Zygote
Once
fertilization
ends…
What’s next?
How many step
happen in animal
growth and
development?
TWO PHASES
1.Embryonic Phase
2.Pasca Embryonic Phase
Egg and Zygote
Polarity
• Most animals have
eggs and zygote with
polarity:
 Animal
pole: low
concentration of yolk.
 Vegetal pole: yolk
concentrated here
1.
EMBRYONIC PHASE
After fertilization…there are 3 major
steps of embryonic phase:
•
•
•
•
Morulation
Blastulation
Gastrulation
Differentiation/
Organogenesis
Animal Embryonic Development
• Stages of development
1. Early Cleavage (Morulation)
• Cleavage begins within an
hour of fertilization; series of
mitotic divisions
• Zygote divides into 2, 4, 8, …
smaller and smaller
blastomeres without increasing
size of embryo
• Cleavage involves about
12 divisions resulting in
solid ball of blastomeres
How are new organisms produced?
In Amphibians
Completed in 24 hrs.
1 and 2 plane is meriodional; 3
equatorial
16-64 cell stage – morula
128 – 15,000 cell stage – blastula
st
nd
rd
is
2. Cleavage - blastulation
• rapid cell divisions
• little cell growth
• packaging of cytoplasmic heterogeneity
• final product is a hollow ball of cells =
blastula
 cells
= blastomeres
 hollow cavity = blastocoel
Cont…
• yolky eggs alter pattern
of divisions
 animal
hemisphere
divides normally
 vegetal (yolky)
hemisphere
• divides less often
• produces larger cells
• amount of yolk affects
cleavage pattern
3. Gastrulation
• Gastrulation - sorts
•
all the cells into
distinct cell layers
(ectoderm,
endoderm, and
mesoderm)
Blastula (hollow ball
of cells) transformed
into the Gastrula
(three layered stage)
Gastrulation
• 1. Gastrulation
begins- Blastopore
formed
Blastopore - midway
opening on one side of
the blastula
-Site of cell migration
from the surface into the
interior (Invagination)
- Future site of anus
•
Gastrulation
2. Cell migrating to
form layers
Archenteron –
primitive gut
formed
(endoderm)
future mouth
•
•
Gastrulation
3.Gastrulation complete Gastrula formed
Endoderm and archenteron replace the blastocoel
Mesoderm - forms a layer
between the ectoderm and
endoderm
Ectoderm- forms the outer
layer.
Yolk plug- (endoderm) marks
the site of the blastopore and of
the future anus
•
•
•
•
Gastrulation in a sea urchin embryo
Key
Future ectoderm
Future mesoderm
Future endoderm
Animal
pole
Blastocoel
1 The blastula consists of a single layer of ciliated cells surrounding the
blastocoel. Gastrulation begins with the migration of mesenchyme cells
from the vegetal pole into the blastocoel.
Mesenchyme
cells
Vegetal
plate
Vegetal
pole
Blastocoel
2 The vegetal plate invaginates (buckles inward). Mesenchyme cells
migrate throughout the blastocoel.
Filopodia
pulling
archenteron
tip
3 Endoderm cells form the archenteron (future digestive tube). New
mesenchyme cells at the tip of the tube begin to send out thin
extensions (filopodia) toward the ectoderm cells of the blastocoel
wall
Archenteron
Blastopore
Mesenchyme
cells
Blastocoel
50 µm
Archenteron
Ectoderm
Mesenchyme:
(mesoderm
forms future
skeleton)
Mouth
Blastopore
Digestive tube (endoderm)
Anus (from blastopore)
4 Contraction of these filopodia then drags the archenteron across
the blastocoel.
5 Fusion of the archenteron with the blastocoel wall completes
formation of the digestive tube with a mouth and an anus. The
gastrula has three germ layers and is covered with cilia, which
function in swimming and feeding.
WATCH THIS VIDEO ….
Differentiation/Organogenesis
•Changing
process of
structure and
function become
specific tissue.
Formation of
organ systems
from germ layers
•
Ectoderm
•Makes up the
outer
covering of
the gastrula
Becomes:
Nervous
system
Epidermis
•
Mesoderm
•Becomes:
Muscles
Heart
Kidney
Dermis
Circulatory,
urinary,
reproductive
system
Endoderm
•Becomes:
Digestive
system
Respiratory
System
Liver
Pancreas
Pasca Embryonic Phase
Maturity and Completing
become more perfect
organism.
There are two divisions
Regeneration
Metamorphosis
1.
2.
1. Regeneration
• Repairing
damage/lost
organ.
Eg. High Animal
Asexual
Reproduction.
Eg. Planaria
•
2. METAMORPHOSIS
1. Insect
a. Ametabole
NO
metamorphosis
- No Larva Stage
- Increasing body
size.
Eg. Book Lice
-
b. Hemimetabola
• Unperfect
Metamorphosis.
Stage:
Egg  Larvae 
semi-imago 
imago/adult.
Eg. Grasshopper
Cockroach
c. Holometabola
• Perfect Metamorphose
Stage:
Egg  Larvae (Instar)
Pupae  Imago/Adult.
Eg. Butterfly
2. Amphibi
• Premetamoprhosis
Fertelized egg  Kecebong
Prometamorphosis
Hind Limb appear and grow slowly.
Climax Metamorposis
Front Limb appear and tail be lost
•
•
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