2. Embryological Development Ch 38.2 & Page 698 Early Animal Development

3. I 1.Development Cell division Growth Differentiation From embryonic tissues to Specialized tissues & organs

4. Embryological Development

5. Meiosis in the Gonads Sperm Meiotic cell division Egg

6. 2. Fertilization of egg in fallopian tube by sperm

7. 3. Zygote formation Fertilized Egg 2n Chromo- some # Union of sperm & egg 1N Sperm + 1N Egg = 2N Zygote

8. 4.Implantation of egg in uterus Fertilization Implantation

9. 5. Cleavage = Splitting by mitosis

10. 3 rd Cleavage= 8 balls “cleave” = To cut Division of embryonic tissue From the zygote to a Multi-ball stage

11. 6.Blastula Hallow “ball” After cleavage Signals the onset of Differentiation of embryo 5 th day blastocyst

12. Hallow Ball or Blastula

13. 7. Gastrula Infolding of cells Follows Blastua stage Forms ? the digestive tract

14. 7.Differentiation “differ” Specialization of embryonic tissue Orders cells into tissues & organs

15. Experimental Studies: DiffeDiffe Cell Differentiation

16. Embryonic Development & the “gray crescent” DiffeDiffe

17. 9.Three cell layers 1. Ectoderm= outer 2. Mesoderm= middle 3. Endoderm= inner Ecto= Skin & nervous Meso= Muscles Bones Endo= Digest. Bladder

18. Neural Tube Development “ Neural”= nervous “tube” = spinal column

19. 10-11.Mammal fetus & uterus Placenta= uterine lining Umbilical cord=connects to uterus Amnion= sack with fluid Fetus = baby

20. Placenta & Umbilical Cord

21. Fetal & Mother’s Blood Mother’s Blood is Separate from the baby! What passes across the placenta? Food, drugs, wastes, alcohol, oxygen What stays behind? Red blood cells How are wastes removed? Diffuse across the placenta (CO2, etc.)

22. Marsupial Pouch

23. Fetus Development

24. 4 Week Embryo

25. Ultra sound scanning

26. Amniocentesis Sampling the amnionic fluid Check for chromosome abnormalities