1. Sexual Reproduction Part 3: Development
Science 9
Ms. Jhaj

2. Human

3. Embryonic Development
After fertilization, zygote undergoes repeated mitosis
-One Cell (zygote)
-2 Cells
-4 Cells
-8 Cells
-Morula: ball of cells by end of 1st week

4. Embryonic Development
By the 2nd week, a hallow ball of cells form, called the blastula.

5. Embryonic Development
Blastula Stage: embryonic stem cells
Next stage: Gastrula which is made out of three layers…

6. Layers of the Gastrula
1) Ectoderm: Outer Layer forms skin and nervous system 2) Mesoderm: Middle layer forms kidneys, muscles, blood vessels, reproductive organs and bones 3) Endoderm: Inner layer forms lungs, liver, and the lining of the digestive system

8. Fetal Development Differentiation: cell layers form organs and tissues
Occurs for 38 weeks
Divide this time into 3 trimesters, each 3 months long

9. Fetal Development Trimester 1: Developing Organ Systems
4 weeks: brain and spinal cord
8 weeks: bone cells and now called Fetus
12 weeks: organ systems formed

10. Fetal Development Trimester 2: Growth Weeks 12-16 rapid growth
Week 20 mother can feel fetus move
Weeks slow growth

11. Fetal Development Trimester 3: Continued Growth
Growth in preparation for birth
Brain grows significantly
Week 32: fat deposited under skin

12. Animation
period of zygote How you were created - 3D animation video of new baby formation

13. Check Your Understanding
BC Science 9 Workbook Pgs 88, 90-91
BC Science 9 Textbook Page 223,
Q’s 10-12, & 20