1. Human Reproduction

2. Objectives: To identify the anatomy of the Male Reproductive System
To understand the hormonal controls in sperm production
To identify the anatomy of the Female Reproductive System
To understand the hormonal controls involved in the 4 stages of the Menstrual Cycle

3. Let’s Compare Male System – simple! Female System – complicated !!
Let’s look at the Male System first.
All it does is produce 2-4 million sperm cells per day starting at puberty and continuing until the day you die!

4. Male Anatomy

5. Cross-section of the Seminiferous Tubule

6. Anatomy of the Seminiferous Tubule
Spermatagonia – 2n reproductive cells that undergo meiosis to produce haploid sperm cells
Interstitial Cells – Produce testosterone
Sertoli Cells – provide nourishment for the developing sperm cells

7. Endocrine System

8. Hormonal Control of Sperm Production
It all starts in your…..BRAIN!!
The Hypothalamus secretes many hormones into your blood including GnRH which stimulates the Pituitary to secrete 2 hormones called: FSH – Follicle Stimulating Hormone LH – Lutenizing Hormone
FSH – stimulates sperm production
LH – stimulates testosterone production

9. Testosterone
Promotes more sperm production AND the development of secondary sex characteristics
Negative Feedback
As levels of testosterone rise the hypothalamus detects the levels and……
…stops the production of GnRH which……
…stops the production of LH which……..
…reduces the production of testosterone
This is called Negative Feedback

10. Hormonal Feedback Hypothalamus Releasing hormone Anterior pituitary
Negative feedback LH
FSH
Sperm production
Testosterone
production

11. Positive feedback
As dropping testosterone levels are detected, the _____________ starts to release ___________, which causes the __________gland to release ____________, which increases the production of ______________.
This is called Positive Feedback

12. Sperm Cells

13. Semen
Semen, not to be confused with “seaman”, is the fluid that sperm cells swim in.
There are three glands that secrete the fluids:
Prostate gland – secretes an alkaline buffer that neutralizes the acidic environment of the vagina.
Seminal vesicles – secrete a fructose solution that provides energy for the sperm cells
Cowper’s gland – secretes a mucous that lines the urethra to prevent the sperm from contacting any urine residue

14. Female Anatomy

15. It all starts in the Brain (again)!

16. Menstrual Cycle
28 day cycle that begins at puberty and continues until menopause
Consists of 4 stages:
Menstruation (your period)
Follicle Stage
Ovulation
Corpus Luteum Stage

17. #1 Menstruation
4-6 days
Endometrium and unfertilized egg are removed from the uterus.
Pituitary gland releases FSH which stimulates the follicles in the ovaries.

18. Ovary and Follicles

19. #2 Follicle Stage
One follicle usually “becomes the chosen one” and continues to enlarge.
The ovaries release Estrogen
Rising levels of Estrogen send negative feedback to the Pituitary stopping the production of FSH and positive feedback initiating the release of LH.
Estrogen causes the endometrium to thicken

20. #3 Ovulation
Around day 14, LH levels are at their highest and cause the stimulated follicle to rupture and release it’s egg.
The egg is swept by the fimbria into the oviduct
You are most vulnerable to becoming pregnant!

21. #4 Corpus Luteum Stage
The ruptured follicle changes into a yellowish structure called the Corpus Luteum.
It releases estrogen and progesterone (pregnancy hormone)
If pregnancy results:
Estrogen and progesterone levels stay high, preventing the release of FSH by the pituitary (NF)

22. Corpus Luteum Stage

23. #4 Corpus Luteum Stage If pregnancy does not occur:
Estrogen and progesterone levels drop, causing the endometrium to deteriorate and menstruation begins again.
Dropping levels of estrogen and progesterone cause the pituitary to begin releasing FSH (PF)

27. Review of the Menstrual Cycle

28. Birth Control Pills Trick your body into thinking it is pregnant.
If your body thinks it is pregnant, you won’t ovulate.
Without an egg being released, you cannot become pregnant.
Each pill has different amounts of progesterone.
The “pill” can be prescribed to regulate your period because of the specific levels of hormones found in each pill

29. Pregnancy Tests
Check for the presence of hCG (Human Chorionic Gonadotrophin) in the mother’s urine
The fertilized egg releases hCG

30. Terms to remember:
Fertilization – union of egg and sperm inside the oviduct. Fertilization and Implantation
Implantation – attachment of fertilized egg into the endometrium 6 to 8 days after fertilization.
Gastrulation – 16 to 18 days after fertilization
Embryo – term used to refer to the developing ball of cells after gastrulation up to 8 weeks.
Fetus – after 8-10 weeks
Make Room For the Baby

31. 8 months
4 weeks
5 months

32. Embryological Development