2. Fertilization and Early Development in Humans Dr. Hughes

4. Fertilization https://www.youtube.com/watch?v=_5OvgQW6FG4

5. FERTILIZATION Joining of sperm & egg – sperm head (nucleus) enters egg

6. (a)Fertilized egg Zygote (b) Four-cell stage (c) Early blastula (d) Later blastula Cleavage

8. Cleavage = Repeated mitotic divisions of zygote http://www.youtube.com/watch?v=itexQak_aWE&list=FLWQwCstNsnemeaoxMc0L8uw

9. GASTRULATION

11. Establish 3 cell layers – ectoderm outer body tissues – skin, nails, teeth – nerves, eyes, lining of mouth – mesoderm middle tissues – blood & lymph, bone & notochord, muscle – excretory & reproductive systems – endoderm inner lining – digestive system – lining of respiratory, excretory & reproductive systems GASTRULATION ectoderm mesoderm

12. NEURULATION Formation of notochord & neural tube – develop into nervous system Notochord Neural tube develops into vertebral column develops into CNS (brain & spinal cord)

13. NEURULATION http://www.youtube.com/watch?v=vgCFPAWMKcI

14. PLACENTA Materials exchange across membranes

15. HUMAN FETAL DEVELOPMENT 7 weeks4 weeks

16. HUMAN FETAL DEVELOPMENT 10 weeks

17. HUMAN FETAL DEVELOPMENT 12 weeks20 weeks

18. HUMAN FETAL DEVELOPMENT The fetus just spends much of the 2 nd & 3 rd trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid Week 20

19. HUMAN FETAL DEVELOPMENT 24 weeks (6 months; 2nd trimester) fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix

20. GETTING CROWDED IN THERE!! 32 weeks (8 months) The fetus sleeps 90-95% of the day & sometimes experiences REM sleep, an indication of dreaming

21. BIRTH positive feedback

22. Intestine Placenta Umbilical cord Wall of uterus Vagina Cervix BIRTH (36 WEEKS) Bladder BIRTH (36 WEEKS)

23. THE END OF THE JOURNEY!