1. Male &
Female
Anatomy

2. Male
Reproductive
System

3. Male Sex Organs
The hormone testosterone regulates the male reproductive cycle and is made by the testes
The testes also produce sperm cells
The scrotum is a sac that contains the testes and provides a cooler temperature for sperm production

4. Males have a penis which is an adaptation for internal fertilization
It allows the male to deliver the sperm into the female

5. Structure of the Sperm Human sperm contain 23 chromosomes (haploid)
A mature sperm consists of a head with very little cytoplasm
Enzymes at the tip of the sperm allow it to penetrate the egg
The Midpiece contains mitochondria that supply energy
The Tail of sperm has powerful flagellum to propel sperm to move through the female reproductive tract

7. Delivery of Sperm
Urethra passes through the penis and carries sperm out of body
During intercourse blood flow to the penis increases, causing the penis to become erect
About 3.5 ml of semen is released which contains million sperm
Few ever reach the egg
Fertilization requires a high sperm count
Males with fewer than 20 million sperm/ml are considered sterile
Sperm survive only 48 hours

9. Sperm penetrating Egg

11. What is in Semen?
Seminal Vessicles – contribute 60% to total volume of semen. Fluid contains large amounts of fructose which provides energy for the sperm
Prostate gland – secretes fluids directly into the urethra. Fluid is thin, contains enzymes and is alkaline (basic) which helps neutralize acids in the urethra and vagina

12. Female
Reproductive
System

13. Female Reproductive System
The hormones estrogen and progesterone regulate the female reproductive system
During ovulation, the mature egg is released from the ovary
It travels down the oviduct (fallopian tube)
If sperm are present the egg will be fertilized in the oviduct

14. If the egg is fertilized, it will travel to the uterus where the embryo develops
If the egg is NOT fertilized, it is shed during her period

15. Gametogenesis in Females:
Gametogenesis = creation of gametes
Occurs in the ovaries
Egg development begins before birth so newborn females have all the eggs she will ever have (~2 million)
Eggs are haploid (contain 23 chromosomes)
During puberty eggs begin to mature
In a lifetime females will only
release eggs

16. Meiosis

17. Ovulation

18. Menstrual Cycle Begins at puberty (~ 12-13 years old)
Ends at menopause (~50 yrs. old)
One egg is released every 28 days
This is called ovulation
Ovulation is regulated by hormones released by the hypothalamus and Pituitary glands

20. Phases of the
Menstrual Cycle

21. 1. Follicle Stage The ovary produces eggs in cavities called follicles
The follicle enlarges and produces the hormone estrogen
During this phase the uterine wall grows and thickens
This stage lasts ~ 14 days

22. 2. Ovulation Stage
During this stage, the egg is released from the follicle and travels through the oviduct (fallopian tube)

23. 3. Corpus Luteum Stage
During this phase, the follicle becomes a mass of cells which produce the hormone progesterone
This causes the uterine lining to thicken with blood vessels
The uterine lining thickens to prepare for embryo development
This stage lasts ~ 12 days
If the egg is
NOT fertilized, then
stage 4…

24. 4. Menstruation Stage
If the egg has not been fertilized, the uterine lining that has been thickening with blood vessels and tissue breaks down and passes out through the vagina along with some blood flow
This stage lasts ~ 4-5 days

25. What happens
if the egg is
Fertilized?

26. Fertilization

27. Fertilization Fertilization is the fusion of gametes (sperm and egg)
It occurs in the oviduct (fallopian tubes)
A human’s gestation period is ~ 9 months after fertilization

28. Do all animals have the same gestation periods?
Human – 266 days Squirrel – 44 days
Camel – 406 days Pig – 113 days
Cat - 62 days Lion – 108 days
Dog – 62 days Kangaroo – 40 days
Dolphin – 276 days Horse days
Elephant – 640 days Giraffe – 400 days

29. How do
Twins Develop?

30. There are 2 types of twins:
Fraternal Twins
Identical Twins

31. Fraternal
Twins

32. 1) Fraternal Twins
Two eggs are produced and fertilized by 2 separate sperm
The result is different genes and therefore different heredity

33. Identical
Twins

34. 2) Identical Twins
A single egg is fertilized by a single sperm, which splits and develops 2 embryos
Result is identical DNA
Identical twins are always the same sex

35. Twins

36. Conjoined
Twins

37. How are they formed?
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.
May be caused by genetic and environmental conditions which are responsible for the failure of twins to separate after the 13th day after fertilization.

38. Is this common?
They are more often female than male (ratio of 3:1) - 70% are female
40% are still born
75% are still born or die within 24 hours
Are more likely to occur in Africa or India than in China or the United States.

39. Types of Conjoined Twins
Conjoined twins are usually classified by the point at which they are joined
There have been as many as three dozen separate types identified in the last century.
The suffix “pagus” is Greek and means “fixed”

40. A) Ischiopagus Shared intestines, bladder, genitals, and kidneys.
Separation survival rate is good.
Although excretion and sexual functions are impaired.

41. Ischiopagus

42. B) Omphalopagus Shared liver
Highest survival rate of all conjoined twins
Liver may be damaged in the operation but quickly regenerates itself.

44. C) Parapagus Shared heart 5% of conjoined cases
Separation possible but artificial limbs will be necessary

45. Parapagus

46. Zygote

47. Zygote Formation
After fertilization occurs, the fertilized egg is called a ZYGOTE
The zygote begins to go through mitosis (cell division) creating the many cells that will form the embryo
As this occurs, the zygote moves towards the UTERUS
This is where the
embryo develops

49. Differentiation

50. Differentiation
During the first part of pregnancy, the DNA will instruct the cells to differentiate
This will allow the cells to become different parts of the embryo
After two months the embryo is called a FETUS
Since the organs are forming in the first trimester (first 3 months of pregnancy) the mother’s actions can impact the developing embryo

52. Differentiation

53. Placenta
When the embryo implants itself in the uterine lining, a PLACENTA begins to form
By the process of diffusion, nutrients and oxygen will pass from mother to fetus
The mom’s blood and baby’s blood DO NOT mix!
The fetus will be protected by a fluid filled sac (amniotic sac)

55. Internal Fertilization
&
Development

56. Why does Internal Fertilization and Development increase the chances for survival?
Most land (terrestrial) animals undergo internal fertilization and internal development
They produce fewer offspring
This is because the chances for survival are higher since the developing embryo is protected inside the mother

57. External Fertilization
&
Development

58. Why do fish produce so many eggs?
Most aquatic organisms (fish) undergo external fertilization and development.
The female lays thousands of eggs, and the male swims over them releasing the semen
Some fish lay up to 10,000 eggs at a time, but few survive due to predators and environmental conditions.

60. Internal
Development
of Humans

61. First
Trimester

62. 3 Weeks
Once in the uterus, the developing embryo, called a blastocyst, searches for a nice place to implant, where it actually burrows beneath the surface of the uterus.
The yolk sac produces blood cells during the early weeks of life.
The unborn child is only 1/6th of an inch long, but is rapidly developing.
The backbone, spinal column, and nervous system are forming.
The kidneys, liver, and intestines are taking shape.

64. 4-5 Weeks
4 weeks - The embryo produces hormones which stop the mother's menstrual cycle.
5 weeks - Embryo is the size of a raisin.
By day 21, the embryo's tiny heart has begun beating.
The neural tube enlarges into three parts, soon to become a very complex brain.
The placenta begins functioning.
The spine and spinal cord grows faster than the rest of the body at this stage and give the appearance of a tail.
This disappears as the child continues to grow.

65. 7 Weeks
7 weeks - Facial features are visible, including a mouth and tongue.
The eyes have a retina and lens.
The major muscle system is developed, and the unborn child practices moving.
The child has its own blood type, distinct from the mother's.
These blood cells are produced by the liver now instead of the yolk sac.

66. 8 Weeks
8 weeks - The unborn child, called a fetus at this stage, is about half an inch long.
The tiny person is protected by the amniotic sac, filled with fluid.
Inside, the child swims and moves gracefully.
The arms and legs have lengthened, and fingers can be seen.
The toes will develop in the next few days.
Brain waves can be measured.

68. 10 Weeks
The heart is almost completely developed and very much resembles that of a newborn baby.
Twenty tiny baby teeth are forming in the gums.

69. 12 Weeks
Vocal chords are complete, and the child can and does sometimes cry (silently).
The brain is fully formed, and the child can feel pain.
The fetus may even suck his thumb.
The eyelids now cover the eyes, and will remain shut until the seventh month to protect the delicate optical nerve fibers.

71. Second
Trimester

72. 18 Week old sucking his thumb

73. 14-16 Weeks
14 weeks - Muscles lengthen and become organized. The mother will soon start feeling the first flutters of the unborn child kicking and moving within.
15 weeks - The fetus has an adult's taste buds and may be able to savor the mother's meals.
16 weeks - Five and a half inches tall and only six ounces in weight, eyebrows, eyelashes and fine hair appear. The child can grasp with his hands, kick, or even somersault.

76. 20 Weeks The child can hear and recognize her mother's voice.
Though still small and fragile, the baby is growing rapidly and could possibly survive if born at this stage.
Fingernails and fingerprints appear.
Sex organs are visible. Using an ultrasound device, the doctor can tell if the child is a girl or a boy.

78. Third
Trimester

80. 24 Weeks
The unborn child is covered with a fine, downy hair called lanugo.
Its tender skin is protected by a waxy substance called vernix. Some of this substance may still be on the child's skin at birth at which time it will be quickly absorbed.
The child practices breathing by inhaling amnionic fluid into developing lungs.

82. 30 Weeks
For several months, the umbilical cord has been the baby's lifeline to the mother.
Nourishment is transferred from the mother's blood, through the placenta, and into the umbilical cord to the fetus.
If the mother ingests any toxic substances, such as drugs or alcohol, the baby receives these as well.

84. 32 Weeks
The fetus sleeps 90-95% of the day, and sometimes experiences REM sleep, an indication of dreaming

86. 40 Weeks
The baby, now approximately 7 ½ pounds, is ready for life outside its mother's womb.
At birth the placenta will detach from the side of the uterus and the umbilical cord will cease working as the child takes his first breaths of air.
The child's breathing will trigger changes in the structure of the heart and arteries which will force all blood to now travel through the lungs.

88. Abby and Brittany Conjoined Twins

89. The End