The Facts of Life: Examining Reproductive Health

Childbirth

Conception and Development

2. Liquid in the fallopian tube washes away the nutrient cells surrounding the ovum, preparing it for fertilization.

3. The ovum.

4. Sperm attempting to move into the uterus through a barrier of cervical mucus.

5. After surviving the acidity of the vagina, only the fittest sperm are able to travel through the narrow passages of the cervical mucus.

6. A spermatogonium traveling through cilia that line the cervix, uterus, and fallopian tubes.

7. White blood cells kill anything foreign to the body, including sperm. These cells are seen here in pale yellow.

8. Sperm trying to penetrate the ovum wall. Only about 100 sperm survive from the original 500 million to encounter the egg.

9. Sperm trying to enter the ovum through its remaining nutrient cells.

10. Two sperm cells entering the craters of the ovum wall.

11. The head of the successful sperm inside the ovum. At this time, the ovum shuts every entry preventing other sperm from entering.

12. Once inside the ovum, the tail, having served its purpose, separates from the head of the sperm.

13. The genetic material from the sperm approaching the egg's nucleus.

14. The fusion of the male's and female's genetic material. This determines the characteristics of the new individual.

15. Slowly traveling towards the uterus by the cilia's movement, the fertilized egg divides.

16. Cell division continues as the egg travels to the uterus.

17. The cells are becoming identifiable. The upper half is the first stage of embryonic development and the bottom half will be the placenta.

18. The fertilized egg has implanted onto the uterine wall. At this time the ovary secretes the hormone progesterone signaling to the pituitary gland that the woman is pregnant and menstruation should not take place.

19. The fertilized egg eight days after conception.

20. At three weeks, the embryo is barely 2 mm (.08 inches) long.

21. The embryo at four weeks, and about 6 mm (1/4 inch) long.

22. The embryo a little over five weeks, and about 1 cm (.4 inches) long.

23. The embryo at six weeks. The heart is beating 140 to 150 beats a minute.

24. The arm at three or four weeks.

25. The arm at about six weeks.

26. The arm at 11 weeks.

27. By 13 weeks, the eyes are well developed.

28. At about 17 weeks, fingernails are discernible.

29. Three-month-old fetus. Surrounding it is the chorionic sac which is attached to the placenta.

30. The 4 1/2-month-old fetus.

31. The fetus at almost six months and covered with downy hair called lanugo. This furry covering protects the fetus from skin infections and makes the baby slippery during birth.

32. The fetus at 8 months is about 45 cm (18 inches) long.