1. 11.4 Sexual Reproduction Nature of science:
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm
Fertilization involves mechanisms that prevent polyspermy
Fertilization in animals can be internal or external
Implantation of the blastocyst in the endometrium is essential for the continuation of pregnancy
hCG stimulates the ovary to secrete progesterone during early pregnancy
The placenta facilitates the exchange of materials between mother and embryo
Estrogen and progesterone are secreted by the placenta once it has formed
Birth is mediated by positive feedback involving estrogen and oxytocin
Nature of science:
Assessing risks and benefits associated with scientific research: the risks to human male fertility were not adequately assessed before steroids related to progesterone and estrogen were released into the environment as a result of the use of female contraceptive pill
Skills:
Annotation of diagrams of seminiferous tubule and ovary to show the stages of gametogenesis
Annotation of diagrams of mature sperm and egg to indicate functions
Applications:
The average 38 week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.

3. Annotate your cells EGG CELL Centrioles Polar cell Plasma membrane
Follicle cells
Gel of glycoproteins
Cortical granules
Cytoplasm
Haploid nucleus
SPERM CELL
Haploid nucleus
Acrosome
Plasma membrane
Centriole
Helical mitochondria
Microtubules
Mid piece
Protein fibres in tail
Tail
Skills:
Annotation of diagrams of mature sperm and egg to indicate functions

6. Sperm and egg production in testes and ovaries
Stage 1
Sperm and egg production in testes and ovaries

7. Oogenesis and Spermatogenesis
Production of egg cells in the ovaries
Spermatogenesis
Production of sperm in the testes in seminiferous tubules
Skills:
Annotation of diagrams of seminiferous tubule and ovary to show the stages of gametogenesis

8. Annotate the ovaries Primary follicle Developing follicles Oocyte
Secondary follicle
Mature follicle (Graafian follicle)
Ovulated ovum
Developing corpus luteum
Corpus luteum
Degenerating corpus luteum
Skills:
Annotation of diagrams of seminiferous tubule and ovary to show the stages of gametogenesis

10. Oogenesis Production of egg cells in the ovary
Starts in the ovaries of a female fetus
Start to divide by mitosis when the fetus is 4-5 months old to develop primary follicles. All genetically identical
No further development until after puberty
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

11. Oogenesis
At the start of each menstrual cycle some primary follicles develop
Only one goes on to produce a mature follicle
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

12. 1. Oogenesis Follicle grows Oocyte divides
Primary follicles consist of an oocyte (cell that can become an ovum) surrounded by a layer of follicle cells
Follicle grows
Oocyte divides
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

13. 2. Oogenesis
Every menstrual cycle, a few primary follicles start to grow and the primary oocyte inside completes one division of meiosis (meiosis I)
Forms a secondary oocyte
First polar body formed from meiosis I
(Small cell that does not then develop further)
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

14. The primary follicle grows and becomes a secondary follicle.
3. Oogenesis
The primary follicle grows and becomes a secondary follicle.
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

15. 4. Oogenesis
A fluid filled cavity develops and the oocyte starts another division of meiosis (meiosis II) producing mature follicles (Graafian follicle)
Second polar body formed
Secondary oocyte is now an ootid
Differentiates into an ovum
Ready for ovulation
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

16. Overview OOCYTE = DIVIDES FOLLICLE = GROWS
Primary oocyte completes meiosis I
Forms a secondary oocyte (and a polar body)
Primary follicles continue to grow into secondary follicles
Secondary follicle containing secondary oocyte
Secondary oocyte completes meiosis II
Now an ootid (and a second polar body)
Differentiates into an ovum
Secondary follicles grow into Graafian follicles
Graafian follicle containing ovum
Ready for ovulation
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

20. Testes have a mass of narrow tubes called the seminiferous tubules
Spermatogenesis
Happens in the testes
Testes have a mass of narrow tubes called the seminiferous tubules
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

21. Spermatogenesis
Outer layer of cells in seminiferous tubules is the germinal epithelium where the production of sperm begins
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

22. Cells have various stages of sperm production
Spermatogenesis
Cells have various stages of sperm production
Most mature cells are closest to the fluid filled centre of the seminiferous tubule.
Cells that have developed a tail are spermatozoa (abbreviated to sperm)
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm

23. Annotate the seminiferous tubules
Germinal epithelium cells
Primary spermatocyte
Secondary spermatocyte
Spermatogonium
Spermatids
Basement membrane
Sertoli cell
Spermatozoa
Skills:
Annotation of diagrams of seminiferous tubule and ovary to show the stages of gametogenesis

24. 1. Spermatogenesis
Germinal epithelium cells (outer layer) divide endlessly by mitosis to make more diploid cells (spermatogonium)
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm

25. Spermatogonium grow larger and are then called primary spermatocytes
2. Spermatogenesis
Spermatogonium grow larger and are then called primary spermatocytes
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm

26. 3. Spermatogenesis
Each primary spermatocyte carries out first division of meiosis to produce two secondary spermatocytes
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm

27. 4. Spermatogenesis
Each secondary spermatocyte carries out second division of meiosis to produce two spermatids each
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm

28. 5. Spermatogenesis
Spermatids become associated with nurse cells, called sertoli cells which help the spermatids to develop into spermatozoa
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm

29. 6. Spermatogenesis
Spermatozoa detach from sertoli cells and eventually are carried out of the testis by the fluid in the centre of the seminiferous tubule
Understanding:
Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.
Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm

32. After sperm and egg production….
Stage 2
After sperm and egg production….
FERTILISATION

33. Fertilisation
Union of a sperm and egg cell to form a zygote in the fallopian tube
Sperm membranes have receptors to detect chemicals released by the egg.
This allows directional swimming.
Multiple sperm will arrive at the egg at the same time.
Understanding:
Fertilization involves mechanisms that prevent polyspermy
Fertilization in animals can be internal or external

34. Preventing Polyspermy
Acrosome reaction
Penetration of egg membrane
Cortical reaction
Understanding:
Fertilization involves mechanisms that prevent polyspermy
Fertilization in animals can be internal or external

36. 1. Acrosome Reaction
Gel of glycoproteins also called zona pellucida which is a layer of proteins around the cell
Acrosome is a large membrane bound sac of enzymes in the head of the sperm
Sperm binds to zona pellucida and the contents of the acrosome are released – including enzymes that digest the zona pellucida
Understanding:
Fertilization involves mechanisms that prevent polyspermy

37. 2. Penetration of egg membrane
An area of the membrane on the tip of the sperm is now exposed.
Plasma membrane of the sperm binds with plasma membrane of the egg
Sperm nucleus enters the egg cell (fertilisation)
Understanding:
Fertilization involves mechanisms that prevent polyspermy

38. 3. Cortical Reaction Nucleus entry causes the activation of the egg
Affects cortical granules first
(vesicles located near the egg membrane)
Contents released by exocytosis
Results in the digestion of binding proteins so that no further sperm can bind
General hardening of the zona pellucida
Understanding:
Fertilization involves mechanisms that prevent polyspermy

39. Types of fertilisation
Internal External
Understanding:
Fertilization in animals can be internal or external

40. Internal Terrestrial animals Some fish
Ensures gametes are in close proximity to each other
Protection inside female
Few babies produced
Understanding:
Fertilization in animals can be internal or external

41. External Most fish Release gametes into water directly
Large number of offspring
Easy to find mates
Susceptible to predation and environmental conditions
(Temperature, pH, pollution)
Gametes not close together
Understanding:
Fertilization in animals can be internal or external

42. Stage 3
After fertilisation….
IMPLANTATION

43. Implantation After fertilisation Ovum divides to form a 2 cell embryo
After 48 hours it becomes a 4 cell embryo
After this, unequal divisions and migration of cells gives the embryo the shape of a hollow ball: blastocyst
Understanding:
Implantation of the blastocyst in the endometrium is essential for the continuation of pregnancy

44. Implantation
At 7 days old the blastocyst reaches the uterus from the oviduct
The zona pellucida breaks down.
The blastocyst has used up the reserves of the egg cell and needs an external supply of food
Sinks into the uterus lining: Implantation
Essential for the continuation of pregnancy
Understanding:
Implantation of the blastocyst in the endometrium is essential for the continuation of pregnancy

45. Implantation
Outer layer of the blastocyst develops finger-like projections allowing the blastocyst to penetrate the uterus lining.
Exchange materials to and from mother’s blood
At 8 weeks it forms bone tissue and is called a fetus
Understanding:
Implantation of the blastocyst in the endometrium is essential for the continuation of pregnancy

47. Stage 4
After implantation….
GESTATION

48. Endometrium
Endometrium must be maintained for the pregnancy to be successful
Progesterone and estrogen must be continually produced
Understanding:
hCG stimulates the ovary to secrete progesterone during early pregnancy

49. hCG hormone
Hormone produced by cells surrounding the embryo which then form the placenta.
Corpus luteum stimulated in the ovary to continue secreting progesterone and estrogen
Continues development of the uterus wall, supplying the embryo with nutrients.
Understanding:
hCG stimulates the ovary to secrete progesterone during early pregnancy

50. Pregnancy week 9 Placenta starts to secrete estrogen and progesterone
Corpus luteum no longer needed so starts to degenerate
Danger of miscarriage if this switch over fails
Understanding:
Estrogen and progesterone are secreted by the placenta once it has formed

51. As a fetus grows the surface area to volume ratio decrease
Placenta
As a fetus grows the surface area to volume ratio decrease
Hard to absorb nutrients
Placenta allows the fetus to remain in the uterus for longer
Understanding:
The placenta facilitates the exchange of materials between mother and embryo

52. Placenta Made of fetal tissues
In contact with maternal tissues in the uterus wall
Amniotic sac also develops from fetal tissues
Contains amniotic fluid which protects and supports the fetus
Understanding:
The placenta facilitates the exchange of materials between mother and embryo

53. Placenta Finger-like placental villi
Increase to help supply growing demands of the fetus
Maternal blood flows in the inter-villous spaces around the villi
Fetal blood circulates in capillaries close to the surface of the villlus
Understanding:
The placenta facilitates the exchange of materials between mother and embryo

54. Placenta Very small distance between fetal and maternal blood
Placental barrier separates maternal and fetal blood
Selectively permeable to allow some substances to pass through
Understanding:
The placenta facilitates the exchange of materials between mother and embryo

55. Placenta From maternal to fetal Glucose (facilitated diffusion)
Oxygen (diffusion)
Antibodies (endocytosis)
Water (osmosis)
From fetal to maternal
Carbon dioxide (diffusion)
Urea (diffusion)
Understanding:
The placenta facilitates the exchange of materials between mother and embryo

56. FETAL BLOOD
PLACENTA
MATERNAL BLOOD
Diffusion
Carbon dioxide

57. Does a baby poop and wee in the womb?
FAQ
Does a baby poop and wee in the womb?
Babies generally do not poop in the womb, given that their digestive systems are not used to process much outside of this swallowed urine. They do accumulate a small amount of fetal poop known as meconium that consists of dead cells, waste, etc, that is pooped out within the first few days of life.
Urinate into aminiotic fluid, then re drink again

58. The Placenta

59. Pregnancy week 9 Placenta starts to secrete estrogen and progesterone
Corpus luteum no longer needed so starts to degenerate
Danger of miscarriage if this switch over fails
Understanding:
Estrogen and progesterone are secreted by the placenta once it has formed

60. Role of progesterone Inhibits Oxytocin secretions
Muscle contractions in uterine wall
Understanding:
Birth is mediated by positive feedback involving estrogen and oxytocin

61. Stage 5
After gestation….
PARTURITION

62. Parturition Time for birth!
Fetus produces hormones to stop progesterone from placenta
Oxytocin is then secreted
Understanding:
Birth is mediated by positive feedback involving estrogen and oxytocin

63. Oxytocin
Stimulates contractions of the muscle fibres in the uterus wall.
Causes more oxytocin to be secreted
Causes more contractions (frequent and vigorous)
Understanding:
Birth is mediated by positive feedback involving estrogen and oxytocin

64. Draw one for oxytocin and contractions
Positive Feedback
Draw one for oxytocin and contractions
Understanding:
Birth is mediated by positive feedback involving estrogen and oxytocin

65. Parturition Muscles in the cervix relax and start to dilate
Uterine contractions cause the amniotic sac to burst
Amniotic fluid leaks out
‘my water has broken’
Understanding:
Birth is mediated by positive feedback involving estrogen and oxytocin

66. Parturition
Hours of uterine contractions later the baby is finally pushed out of the cervix and vagina
Umbilical cord is broken and the baby takes its first breath – being independent from its mother.
Understanding:
Birth is mediated by positive feedback involving estrogen and oxytocin

67. Create a dramatic monologue to describe what happens during parturition to perform in front of the class.
Progesterone
Contractions
Uterus wall
Oxytocin
Secretion
Vigorous
Frequent
Positive feedback
Relaxation
Cervix
Dilate
Amniotic sac
Amniotic fluid
Vagina
Umbilical cord
Independence

68. Altricial Helpless Incompletely developed offspring
Relatively immobile
No hair
Cannot obtain food themselves
Applications:
The average 38 week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.

69. Precocial Open eyes Hair Immediately mobile
Able to defend for themselves somewhat
Larger mammals
Longer gestation period
Applications:
The average 38 week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.

70. What are we? Open eyes Some hair Not mobile Can’t defend for ourselves
Cannot obtain food for ourselves
Applications:
The average 38 week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.

71. INTERMEDIATE Open eyes Some hair Not mobile Can’t defend for ourselves
Cannot obtain food for ourselves
Applications:
The average 38 week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.

72. Correlation between mammalian body mass and gestation period
Applications:
The average 38 week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.