2. (C) Gametogenesis Process by which gametes are produced in the gonads Two types: - Spermatogenesis - Oogenesis

3. Oogenesis The primary oocyte goes through first meiotic division and the cytoplasm of the cell is divided unequally The larger daughter cell is called the secondary oocyte and the smaller daughter cell is called the polar body During second meiotic division, 1 mature ovum is produced and 3 polar bodies

4. Spermatogenesis Primary spermatocyte goes through first meiotic division and form two daughter cells of equal size Each daughter cell (secondary spermatocyte) goes through the second meiotic division forming four motile sperm cells of equal size

6. Comparison of Ova and Sperm Egg cells contain stored food in the form of yolk Egg cells are larger than sperm Sperm are motile, egg cells are not

7. (B) Fertilization The fusion of the nuclei of one sperm with one ova (egg) to produce a zygote Sperm (n) + Ovum (n) =2n Sperm (23) + Ovum (23) = 46

8. Parthenogenesis An embryo develops from an unfertilized egg typically involves the development of eggs into viable offspring from females without fertilization by sperm.. Parthenogenesis is no longer only for lower invertebrates, such as aphids, mites and nematode worms--it's also been found in fish, bees, birds and lizards. the second polar body -- the daughter cell produced along with the egg in the second stage of meiosis -- acts like a sperm and re-enters the egg. Essentially the egg fertilizes itself! As this polar body contains identical genetic material to the egg, having been produced by normal division of an already haploid cell, the resulting diploid cell has only half the genetic diversity of the female's original cells. Thus fewer bands appear in the DNA fingerprint of the offspring.

9. Parthenogenesis

10. Fertilization Union of a haploid sperm nucleus with a haploid egg nucleus This results in a diploid zygote with the full number of chromosomes n n 2n

11. Fertilization Union of a haploid sperm nucleus with a haploid egg nucleus This results in a diploid zygote with the full number of chromosomes

12. Fertilization and the Stages of Mitosis

13. Two types of Fertilization External Fertilization Internal Fertilization **Parthenogenesis**

14. Eggs are fertilized outside the body of the femaleEggs are fertilized outside the body of the female Large number of eggs are requiredLarge number of eggs are required This type of fertilization is found in an aquatic environmentThis type of fertilization is found in an aquatic environment Ex: fish and frogs Ex: fish and frogs External Fertilization

15. Spawning??? http://www.umces.edu/2002Session/oyster.html

16. External Fertilization

20. What are some differences between External and Internal Fertilization? Provide examples!!!

21. External Fertilization

25. Internal Fertilization Takes place inside the body of the female Less eggs are required Ex: mammals, birds and reptiles

26. Internal Fertilization

27. The embryo arrives in the uterus 5-10 days after fertilization The embryo implants into the uterine wall and establishes pregnancy Placenta- nourishes the embryo Umbilical cord- attaches the embryo to the placenta Amnion- embryo develops inside the amniotic sac which contains amniotic fluid that serves as a shock absorber Gestation Period- length of pregnancy (approximately nine months)

28. Fertilization

29. Good Review Webpage http://regentsprep.org/Regents/biology/biology.cfm

30. Implantation of blastocyst Day 7 Fertilization Day 4 Day 3 Day 2 Day 1 Day 0 Egg released by ovary Fertilization and Implantation Section 39-4 Uterine wall Blastocyst Morula 4 cells2 cells Zygote Ovary Fallopian tube http://regentsprep.org/Regents/biology/units/reproduction/index.cfm http://regentsprep.org/Regents/biology/biology.cfm

31. Development The zygote, which is a fertilized egg consisting of one cell, will begin to divide rapidly by mitosis forming the early developing human embryo. Fertilization and the initial stages of this mitotic cell division occur in the oviduct. The early embryo is migrates down the fallopian tube and completes most of its development in the wall of the uterus.

32. Do Now Looking at the diagram above. Hypothesize the systems that will develop from these three layers. Reproductive Muscles, Skeleton Digestive Nervous ETC Ectoderm Mesoderm Endoderm

33. It is the three germ layers that give rise to all the tissues and organs of an animal EctodermMesodermEndoderm Nervous system Digestive System lining of mouth, nostrils, and anus epidermis of skin, sweat glands, hair, and nails bones and muscles blood and blood vessels reproductive and excretory system dermis layer of skin lining of digestive tract lining of trachea, bronchi, and lungs liver, pancreas thyroid, parathyroid urinary bladder

34. The Three germ layers

35. Do Now Identify what is the purpose of the following: The placenta: The umbilical cord:. The amniotic fluid:

36. Do Now answers The placenta is a combination of maternal and fetal tissue which allows for the exchange of materials with the fetus and mother. Needed materials such as food and oxygen diffuse through the placenta to the fetus, while wastes from the fetus diffuse to the mother. The umbilical cord is a fetal structure containing blood vessels which allows materials to be carried between the fetus and placenta in both directions. The amniotic fluid surrounds the fetus and helps to provide a shock absorber to protect the fetus against mechanical injury in the event the mother is shaken or injured in some manner.

37. Human Development

38. Fetal Development Development is a highly regulated process After this small cluster of cells called the gastrula forms in humans, tissues begin to form. In humans, the embryonic development of essential organs occurs in early stages of pregnancy. During the first three months of human development, organs begin to form. The human embryo is usually referred to as a fetus when human like features become visible in its structure. All organs and body features are developed by the end of the sixth month. During the last three months of pregnancy, organs and features develop well enough to function after birth.

39. What are some things that could affect fetal development? 6 weeks 4 months

40. What are some things that could affect fetal development? The embryo (or fetus) may encounter risks from faults in its genes and from its mother's exposure to environmental factors such as: inadequate diet use of alcohol (Fetal alcohol syndrome) Tobacco Drugs other toxins infections

41. Reproductive Technologies Reproductive technology has medical, agricultural, and ecological applications. In many instances, these technologies have progressed at a faster rate than the ethical considerations resulting from these technologies. Some of these techniques include birth control methods used to block the process of fertilization. Many technologies now exist to enhance the process of fertilization and development in humans and other organisms. Amniocentesis Hormone therapy can cause increased egg production. Surgery can open blocked fallopian tubes in females and the vas deferens in males. In vitro fertilization (test-tube babies) is a widely used technique to aid infertile couples, allowing them to have children where this otherwise would not be possible.

42. Amniocentesis Fetal cells are removed and surveyed for genetic disorders

43. Reproductive Technologies

45. (IV) Multiple Births 1. Identical twins- Develops from one zygote separating into two during cleavage. One sperm and one egg is involved and therefore the babies will look identical and must be of same sex

46. (IV) Multiple Births 1. Identical twins- Develops from one zygote separating into two during cleavage. One sperm and one egg is involved and therefore the babies will look identical and must be of same sex

47. Identical twins do not have identical fingerprints. They are a product of their environment.

49. Conjoined Twins

50. Conjoined “Siamese” Twins Chang and Eng

51. Eng Bunker---Chang Bunker Born: May 11, 1811 Died: January 11, 1874

52. The developing embryo begins to split into identical twins but then stops part way leaving the partially separated egg to mature into a conjoined fetus.

53. They are more often female than male (ratio of 3:1)

54. They occur as often as once in every 40,000 births but only once in every 200,000 live births.

55. 40% are still born 70% are female - even though monozygotic twins are more frequently male than female. 75% are still born or die within 24 hours.

56. Cephalophagus

57. Dicephalus This refers to one body with two heads.

58. Ischophagus Anterior union of the lower half of the body

59. http://www.conjoined-twins.i-p.com/

60. Conjoined twins Parasitic twins: Asymmetrical conjoined twins, one twin being small, less formed, and dependent upon the other. Fetus in fetu: Situation in which an imperfect fetus is contained completely within the body of its sibling.

61. (V) Multiple Births Fraternal twins- Develop from two separate eggs, each fertilized by separate sperm cells. Therefore, the babies may not look identical and could be of different sex. Simply ciblings!

62. (V) Multiple Births Fertility drugs often cause production of more than one ovum during ovulation. Septuplets = 7 ova + 7 sperm (7 zygotes)

63. (V) Multiple Births