Transcript Embryology Power Point Link

Embryology of
Chicks
Fertilization forms Blastoderm
 All organisms start as one cell called an egg
or ovum. This “true egg” is located on the
outside of the yolk of an egg in a small spot
called the blastodisc (germinal disc).
 This cell must be fertilized by the male germ
cell or sperm. This sperm will enter the
blastodisc (germinal disc).
 The fertilized egg begins to divide into a
cluster of cells called the blastoderm.
Blastodisc on yolk
Fertilized Blastoderm
First Stages
of
Development
First Stages occur inside of hen
 The early stages of development to form a
blastula take place inside the hen as the egg
forms.
 This will occur until the egg is laid.
 Once the egg is laid the development pauses
until it is incubated.
 Incubation is the time required for the
development of an organism under proper
environmental conditions.
Gastrulation Stage
 Once incubation occurs the blastula will continue to form.
 All of the cells in the blastula are exactly the same.
 Then a stage called a gastrula forms. The blastula caves in
forming layers.
Cells Become Different!!
 During gastrulation some of
the cells on the surface move
into the center of the ball of
cells forming three separate
germ layers:the endoderm,
mesoderm and ectoderm.
 This is the first time the cells
begin to differentiate and
become specialized for the
job they will need to perform
for the organism.
 http://worms.zoology.wisc.e
du/frogs/gastxen/wholegas.
html
Primary Germ Layers
 Endoderm- the most internal germ layer,
forms the lining of the gut and other internal
organs.
 Ectoderm- the most exterior germ layer,
forms skin, brain, the nervous system and
other external tissues.
 Mesoderm- the middle germ layer, forms
muscle, the skeletal system and the
circulatory system.
Chick Day 1 (24 hours)
Chick Day 2
Chick Day 3 Page 1
Chick Day 3 Page 2
Chick Day 4
http://www.youtube.com/watch?v=Bzvpa1SaGgY
Chick Day 5
Extra Embryonic Membranes
 Yolk sac- Grows over yolk to absorb
yolk material.
 Amnion- Sac filled with fluid that
surrounds and protects chick.
 Chorion- Surrounds both the
amnion and yolk sac and fuses with
the allantois to help absorb calcium
from the shell.
 Allantois- Blood vessels bring
oxygen to the embryo and take
carbon dioxide away. Also, stores
excretions (wastes), absorbs
albumen and calcium from shell for
the building of the bones. Stops
functioning when chick breaks
through air cell and starts to breathe
on its own.
Chick Day 6 Page 1
Chick Day 6 Page 2
Chick Day 7 Page 1
Chick Day 7 Page 2
Chick Day 8
Chick Day 9
Chick Day 10
Chick Day 11
Chick Day 12
Chick Day 13
Chick Day 14
Chick Day 15
Chick Day 16
Chick Day 17 Page 1
Chick Day 17 Page 2
Chick Day 18
Chick Day 19
Chick Days 20-21 WAITING!!!!!
An Amazing Process!!!