1. Human Embryology

2. Fertilization Fertilization- results in a zygote
-requires the sperm & egg nucleus to fuse

3. Sperm Structure Sperm- made of 3 parts
head- contains haploid nucleus & acrosome
(enzymes that allow sperm to penetrate the egg)
middle piece- contains mitochondria (make energy; ATP)
tail- flagellum- allows sperm to swim toward the
egg

4. Egg Structure Egg structure contains 3 parts
-plasma membrane, vitelline envelope, jelly coat

5. Fusion of egg and sperm

6. Female Reproductive System

7. Fertilization Process
Acrosome enzymes of sperm digest away the jelly coat
Acrosome extends a filament that attaches to a receptor on vitelline envelope (like a lock & key)
Nuclear membrane of sperm & plasma membrane of egg fuse

8. Fertilization Process (cont.)
Sperm nucleus enters the egg
Zygote forms when sperm nucleus & egg nucleus fuse
Following fusion, the egg plasma membrane & vitelline envelope undergo changes that prevent the entrance of other sperm
Vitelline envelope becomes the fertilization envelope

9. Fertilization Process
After egg is released from the ovary it moves into the fallopian tube and waits for the arrival of the sperm and fertilization to take place
Then wave-like action of cilia move the fertilized egg toward the uterus for implantation to take place

11. Fertilization of female egg

12. Development- all the changes that occur during the life of an organism
Embryo- 1st stages of development of an organism after the zygote forms

13. Cell Division 1…2 buckle my shoe
Embryonic Development (Continued)
-zygote undergoes cleavage (cell division w/o growth)- mitosis and DNA replication occur repeatedly
Once the zygote is formed it begins to divide through a process called cleavage.
Upon completion of the first division, you have two cells. Then these two cells divide to form four cells.

15. Deuterostomes vs. Protostomes SAY WHAT???
8-CELL STAGE IS KEY DIFFERENCE!!!-Deuterostomes- (starfish & vertebrates) cleavage results in 8 cells sitting directly on top of each other. This is called radial cleavage

16. Protostomes
protostomes (clams, worms, & insects) undergo spiral cleavage- cells divide and they do not sit on top of each other; they appear to spiral

17. Morula
The eight cells now continue to divide until you are simply a large solid ball of cells (16-32 cells).
Morula

18. Blastula
At this time, the morula begins to form a hollow ball of cells called the blastula.
The blastula contains a fluid filled space known as the blastocoel.

20. Gastrula
Now gastrulation occurs. The hollow ball of cells known as the blastula begins to fold inward on one side
(imagine that you had a deflated basketball and pushed it in on one side).
When the folding occurs, it begins to create a horse shoe shaped structure that is 2 cell layers thick..

21. Gastrula (cont.)
The outer layer of the ball is called the ectoderm. The inner layer of the ball is called the endoderm.
Eventually, another cell layer will begin to form between the endoderm and ectoderm. This layer is called the mesoderm.
The point where the horse shoe almost touches is called the blastopore (small hole).
In protostomes this will eventually form the mouth.
In deuterostomes this will form the anus.

22. 3 tissue layers Ectoderm- forms nervous system & outer layer of skin
Mesoderm- forms muscle, bone, &
cardiovascular system
Endoderm- organs of digestive system,
lining of respiratory system &
bladder

23. What do the 3 layers become?