1. Human Development and Birth
Sexual Reproduction
Human Development and Birth

2. The Male Reproductive System

3. Male Gonads =Testes It produces (male sex hormone)
Testosterone
sperm formation happens in the seminiferous tubules of the testes
The is the sac that contains the testes.
Scrotum
Sperm are stored in the epididymis on top of the testes

4. This tube connects with the & leads out of the penis
When it’s time the sperm travel through a duct/tube called the vas deferens
This tube connects with the & leads out of the penis
Urethra
The sperm pass by glands that add fluids to form .
semen
The semen nourishes & protects the sperm from the acidic environment of the woman's vagina
seminal vesicles: secretes a fluid high in protein.
prostate gland: neutralizes urethra

5. = Male reproduction organ
The is used by both the excretory & reproduction systems.
Urethra
= Male reproduction organ
Penis
An adaptation for internal fertilization. Gets the sperm into the female's reproductive tract

6. Male Reproductive System
The Tubes within the
Male Reproductive System

7. Urinary bladder
Pubic bone
Vas deferens
Urethra
Penis
Seminal Vesicle
Large intestine
Prostate gland
Rectum
Scrotum
Epididymis
Testis

8. Why would the uterine lining need to be thick???
Ovaries
OVARY
OVIDUCT
Female Gonads =
Contain immature (ova)
eggs
Produces many hormones: estrogen – thickens lining of uterus & progesterone – maintains thick uterine lining.
Why would the uterine lining need to be thick???
MENSTRUATION – A woman’s period

9. Oviduct = Fallopian Tubes
After ovulation, the egg is transported through the (a.k.a. Fallopian tubes) heading towards the uterus
Oviduct
If any sperm are around, this is where the egg is fertilized.
OVIDUCT

10. Uterus Thick walled, and muscular.
OVARY
Thick walled, and muscular.
Where the embryo implants & develops
Cervix
Lower end of the uterus is
The is opening for baby (birth canal)
Vagina

11. The Female Reproductive System
Fallopian tube
Ovary
Urinary bladder
Pubic bone
Urethra
Vagina
Uterus
Cervix
Rectum

12. The Egg Each ovary contains about 200,000 tiny egg sacs called = .
Follicles
Each follicle contains an immature
egg
When the follicle ruptures releasing the egg, it is called
Ovulation
Oviduct
The egg is pulled into the
If fertilized=Zygote, will embed into uterus

13. The Menstrual Cycle begins at puberty and ends at menopause
usually lasts approximately 28 days
can vary due to many factors. Like what?
there are 4 stages to the menstrual cycle

14. What is this an example of??!!
Follicle stage
·    FSH (follicle-stimulating hormone), produced by the pituitary tells the egg to mature
·    Estrogen is produced from the ovary to build up the uterine lining (blood vessels) in case the embryo implants & to stimulate ovulation
·      ~days 1-14 of the cycle
What is this an example of??!!
NEGATIVE FEEDBACK

16. The Menstrual Cycle

17. Ovulation the mature egg is released from the follicle around day 14
the high levels of luteinizing hormone stimulates the ruptured follicle to transform into the corpus luteum

19. Release of Egg from Follicle

20. Corpus luteum stage
the corpus luteum secretes progesterone which maintains the uterine lining if fertilization/implantation
~days of the cycle

21. Menstruation
·    if no zygote is implanted into the uterus, the uterine lining breaks down  
·    the lining of the uterus pass out of the body through the vagina
·      ~ days of the cycle

22. Remember Meiosis?? Specialized sex cells or gametes (Sperm & Egg)
Cells created have only half the number of chromosomes
The nuclei of the gametes fuse during Fertilization.

23. Forms of Fertilization
&
Development
Fert/dev
Fertilization: fusion of haploid sperm and haploid egg

24. External Fertilization &
External Development
Fish Eggs

25. External Fertilization & External Development

26. Internal Fertilization External Development
Turtle Egg Sac

27. External Development
Turtle Eggs

28. External Development

29. External & Internal Fertilization
Does not need water environment
Male introduces sperm into the female body
Only 1 egg needed
Ex.) Sharks, lobsters, humans
No “scattering” of gametes outside, fewer eggs used.
Timing is key- fertilization can only occur 24 hrs after egg is released.
Need a water environment
Male will “fertilize after the female has laid eggs
Large numbers of eggs and sperm needed
Ex.) Salmon, Fish, Amphibians
More offspring, Hormonally controlled behavior
Eggs may eaten by other animals, may die from temperature, O2 content

30. Internal Fertilization & Internal Development

31. Fertilization and Implantation
Day 0
Day 1
Implantation of blastocyst
Fertilization
Egg released by ovary
Uterine wall
Blastocyst
Morula
Zygote
Ovary
Fallopian tube
Day 3
Day 2
Day 4
Day 7

32. The fertilized egg makes the journey through the Fallopian tube to the uterus, where it will implant.

34. Human Development and Birth
Clip..\biomovies\humanembryonicdevelopment.mov
Human Development and Birth

35. Fertilization in Humans
after ovulation, fertilization usually occurs in the oviduct- formation of a zygote
if not fertilized within ~24 hours, the egg deteriorates & can no longer be fertilized
cleavage begins in the oviduct
~ 6-10 days later, the developing embryo (now a blastula) may be implanted in the lining of the uterus
gastrulation & differentiation occur after the embryo has been implanted in the uterine walls

36. Pre- natal Development
first 2 months are the most important! (cells become specialized—differentiation)
leads to low birth weight (less than 5 pounds at birth), which is the leading cause of developmental disability--lots of problems
possible cerebral palsy, seizure disorders, immature organs, non-developed immune system
THIS CAN BE PREVENTED!
CHEMICALS IN YOUR BLOOD CAN ALSO GET INTO YOUR DEVELOPING CHILD'S BLOOD

37. An eight-celled pre-embryo
EARLY STAGES OF EMBRYONIC DEVELOPMENT (Zygote undergoing mitosis)
                                                           A zygote
                                                    An eight-celled pre-embryo

38. CHANGES IN THE ZYGOTE

39. The “Germ” Layers Ectoderm: Mesoderm: Endoderm:
Forms the nervous system,
Skin, lining of mouth, hair, nails
Mesoderm:
Muscles and Red Blood
Cells
Endoderm:
Lines of the inside of
Respiratory tract, digestive tract, endocrine glands

40. First Week to Third Week
Pregnancy
First Week to Third Week
The ovum (egg) is in the uterus.
Inside this egg sac is the tiny embryo
The primary divisions of the brain are visible
Fourth Week to Sixth Week
The cerebrum begins to appear.
The ends of the fingers & toes can be recognized.
Seventh and Eighth Weeks
The upper lip is completed, The eyelids are present

41. First Trimester: From Embryo to Fetus
The embryo at six weeks

42. The fetus at 12 weeks Third Month.— eyelids meet and fuse,
the limbs are well developed
The external organs are differentiated that it is possible to distinguish the sex.
The fetus at 12 weeks

43. Second Trimester: The Growing Fetus
The hairs begin to make their appearance.
There is an increase in size
Umbilical cord- attaches embryo to the wall of the uterus
The fetus at 14 weeks

44. The fetus at 20 weeks The first movements are observed
Placenta- exchanges nutrients, gases, and wastes through diffusion across blood vessels
The fetus at 20 weeks

45. Seventh Month Eyelids are open The weight 3lbs
The body is covered by fine hairs
The fetus at 24 weeks

46. Third Trimester: The Final Weeks
Eighth Month
The skin becomes pink
The weight is between 4-6 lbs
Ninth Month
Fetus weighs from 6-10 lbs
The fetus at 32 weeks

47. Birth What are the three stages of birth?
1. Dilation- mild contractions of the uterine muscles; oxytocin is released to stimulate contractions and dilation of cervix ; amniotic sac ruptures
2. Expulsion – contractions force baby through the cervix to the birth canal; mother assists by contracting and “pushing”
3. Placental stage- after birth of baby, placenta seperates from the uterine wall, umbilical cord is clamped
Birth

48. Birth- the process by which a fetus is pushed out of the uterus and the mothers body
Labor- the physiological and physical changes a female goes through to give birth

49. It’s Twins!!
If more than one egg is produced, you can have more than one embryo
FRATERNAL TWINS
IDENTICAL TWINS
*2 eggs and 2 sperm
*2 eggs get fertilized
*1 egg and 1 sperm
*1 egg gets fertilized
*zygote splits during cleavage