2. What is Embryonic Development?
Embryonic Development is when
the embryo is formed and develops.
It starts with the fertilization of a
egg, which after is called a zygote.
The zygote goes through rapid
divisions.
The scientific name for it is
Embryogenesis.
3. Stages of Embryonic Development
Embryonic Development has 4
stages:
Cleavage
Patterning
Differentiation
Growth
4. Cleavage
Cleavage is the first stage of
embryonic development.
In this stage the cell starts to
divide. Each with the exact genes in
the zygote. It is controlled by the
mother’s genes.
In the end of the process of
Cleavage the zygote is now called a
blastula.
6. Patterning
This is the second phase.
During this phase the cells produced by Cleavage
organize themselves in layers and masses.
o Parts of the organism that develop:
Front and the rear.
Back side and belly side.
Left and right side.
During this process three major germ layers are
formed:
Ectoderm
o Mesoderm
o Endoderm
o By the end of this process the zygote’s genes are
expressed.
7. Differentiation
This is the third stage.
It starts to make specialized
structures and has more functions.
The body now produces neurons,
skin cells, muscle cells and etc.
The organized into tissues, the
tissues organize into organs, and
the organs into systems.
8. Growth
This is the last
stage.
In this stage the
organism goes
through a period
of growth.
New cells are
formed and more
extra cellular
matrix.
9. The First Trimester
The first trimester is when the cell starts
to divide.
The zygote begins to develop.
At the end of this trimester the:
Head is round
Eyes are closed
Taste buds are forming
The internal organs move into the body cavity
Upper and lower limbs are formed.
10. The Second Trimester
In the second trimester the baby is
becoming more developed. The
baby develops more.
At the end of the trimester:
The baby’s eyes are open.
The sex is determined.
The baby weighs 12.5 ounces.
Bones and muscles are growing
steadily.
11. The Third Trimester
In the third trimester the baby is developing.
What is developed:
Footprints and fingerprints are formed
Eyelids open and close
Brain development grows rapidly
The baby is born
