1. Adaptations for Sexual Reproduction
Human Reproduction
Adaptations for Sexual Reproduction

2. Section Outline The Reproductive System Sexual Development
Role of Hormones
1. Pituitary Hormones: FSH + LH
2. Testes: Testosterone
3. Ovaries: Estrogen + Progesterone
C. The Male Reproductive System
1. Sperm Development
2. Sperm Release
D. The Female Reproductive System
1. Egg Development
2. Egg Release
E. The Menstrual Cycle
1. Follicular Phase
2. Ovulation
3. Luteal Phase
Menstruation

3. Hormones and Human Reproduction
Hormones are powerful “chemical messengers” produced by Endocrine Glands.
Hormones regulate most life activities (directly or indirectly); including the onset of sexual maturity (Puberty)
The development of gametes and secondary sex characteristics are controlled by the INTERACTION of hormones produced by the Hypothalamus and Pituitary glands (brain) and hormones produced by the male and female gonads.

4. The Brain-Gonad “Connection”
Hypothalamus
The hypothalamus makes hormones that control the pituitary gland. In addition, it makes hormones that are stored in the pituitary gland.
Pituitary gland
The pituitary gland produces hormones that regulate many of the other endocrine glands.
Ovary
The ovaries produce estrogen and progesterone. Estrogen is required for the development of secondary sex characteristics and for the development of eggs. Progesterone prepares the uterus for a fertilized egg.
ovary
Testis
The testes produce testosterone, which is responsible for sperm production and the development of male secondary sex characteristics
testes

5. Hormones controlling Male Repro
Two hormones produced by the Pituitary Gland (located in brain) are:
FSH (follicle stimulating hormone) – “targets” testes to develop mature sperm
LH (luteinizing hormone) – acts on the testes to produce testosterone
Testosterone, is produced in the testes and is the primary sex hormone in males.

6. Action of Testosterone
A sudden increase in Testosterone
Initiates male puberty
Acts to develop secondary male sex characteristics
Development of Male Sex Organs
Greater Bone and Skeletal Muscle Mass/density
Growth of Beard and Body Hair
Lowering of Voice

7. Male Reproductive Structures
Urinary Bladder
Pubic Bone
Vas deferens
Large intestine
Urethra
Penis
Cowper’s
Gland
Seminal
Vesicle
Rectum
Epididymis
Scrotum
Prostate
Testes
Coiled Seminiferous Tubules

8. Main Functions of Male Repro System
Sperm production in paired testes
Requires lower temperature
Scrotum adaptation for max. sperm production
Flagellum
Mitochondria
2. Delivery of Sperm into Female’s Reproductive Tract
Head
Nucleus

9. Cross-section of Testes
Site of Sperm and Testosterone Production

10. Female Repro Structures
Fallopian tube
Fallopian Tube
Ovary
Urinary Bladder
ovary
Uterus
Pubic bone
Urethra
Cervix
Vagina
Vagina
Rectum

11. Cross-section of Ovary
Follicles at various stages of Development (photo)
Follicles produce eggs, Estrogen and Progesterone
ONLY one
Follicle/ month will
Produce the egg
That’s ovulated
follicle
Egg

12. Egg maturation in ovary
releases progesterone
maintains uterus lining
produces estrogen

13. Human Menstrual Cycle

14. Menstrual cycle Controlled by interaction of 4 hormones FSH & LH
estrogen
progesterone
FSH
ovulation = egg release
egg development
corpus luteum
estrogen
progesterone
lining of uterus
days 7 14 21 28

15. Four Hormones Regulate the Menstrual Cycle
Pituitary Gland produces FSH (follicle stimulating hormone) + LH (lutenizing hormone)
Pituitary
Gland ↑
Pituitary
Releases FSH;
Stimulates the
Maturation of
Follicles and
Estrogen
production
↑Estrogen causes
Release of LH
↑ LH causes
Ovulation
Corpus luteum
Secretes progesterone
Follicles in the Ovaries produce estrogen and progesterone

16. Menstrual Cycle Summary Chart
Follicle Stage
↑FSH
Follicle develops
Follicle produces Estrogen
Egg Matures
Estrogen Thickens Uterus lining
Lasts days
Low Estrogen + progesterone allows FSH to be released again from pituitary
Day 14
4. Menstruation
Sudden decrease in
estrogen and progesterone
Shedding of Uterine Lining
2. Ovulation
↑ LH released
Mature egg released
Ovulation
Lasts days
3. Corpus Luteum Stage
Ruptured follicle becomes the Corpus Luteum (yellow Body)
Corpus luteum produces Progesterone
Uterus lining becomes thicker, prepares
For possible fertilization
Corpus luteum
Degenerates
Causing
Progesterone
+ estrogen to
Drop

17. Fertilization Occurs In the Fallopian Tubes
Day 4
4 cells
2 cells
Zygote
Morula
Day 7
Fertilization
Blastocyst
Day 0
Implantation of blastocyst
Uterine wall
Egg released
“ovulation”
ovary

18. Early Embryonic Development
All divisions of
A zygote after
Fertilization are
Mitotic cell
divisions
Called Cleavage

19. The Three Germ Layers Differentiation of Cells
Endoderm:
Lining of Digestive
And Respiratory tracts,
Liver and Pancreas
Mesoderm:
Muscles and Skeleton,
Circulatory and
Reproductive systems
Ectoderm:
Nervous System
Epidermis of skin

20. Multiple Births
Fertilization is the fusion of a sperm and an egg to form a zygote, the single cell from which all cells of the human body are derived. When an egg is fertilized, the remarkable process of human development begins.
1. If two eggs are released during ovulation, each can be fertilized by a sperm. What do you think would be the result? Explain your answer.
2. If one zygote splits into two, each can continue development on its own. What do you think would be the result? Explain your answer.
3. Triplets are three babies born at the same time. Describe three ways that triplets could develop.

21. Fetus to Baby In spite of the placental “barrier” Small molecules and
Viruses can still cross
And affect the baby
Alcohol (FAS)
Carbon Monoxide (Smoking)
Narcotics (Heroine, Crack)
HIV
Measles
Chicken Pox
Antibodies
Rh incompatibility

22. Placenta
Food & gases diffuse across blood vessels

23. Human Embryo: 3-8 weeks Gestation
Note, the period from week 12 to week 38 is considered Fetal Development

24. Human fetal development
10 weeks

25. Human fetal development
12 weeks
20 weeks

26. Human fetal development
The fetus just spends much of the 2nd & 3rd trimesters just growing
…and doing various flip-turns & kicks inside amniotic fluid
Week 20

27. Human fetal development
24 weeks (6 months; 2nd trimester)
fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix

28. Human fetal development
30 weeks (7.5 months)
umbilical cord

29. positive feedback
Birth

30. Birth (36 weeks) Intestine Placenta Umbilical cord Wall of uterus
Bladder
Cervix
Vagina

31. And you think 9 months of Biology is hard!
The end of the journey!
And you think 9 months of Biology is hard!