1. Human Reproductive System
Objectives:
Identify the major structures of male and female reproductive system
Describe the function of each structure of the reproductive system
Describe how sperm and eggs are produced.
Summarize the stages of the ovarian cycle
Describe the stages of pregnancy
Summarize the development of an embryo during gestation

2. Types of Reproduction
Asexual – does not involve the union of gametes; a single parent donates the entire genome to offspring
Limits the amount of variation in phenotypes of offspring
Makes organism vulnerable environmental changes
Sexual – production of offspring from the combination of genetic material from two parent organisms
Increases the variation of phenotypes in offspring
Increases the rate of survival of a species when environmental factors change
Parents must produce sex cells through meiosis
Produces 4 haploid cells from a single germ cell

3. Sexual Reproduction: An Evolutionary Enigma
Sexual females have half as many daughters as asexual females; this is the “twofold cost” of sexual reproduction
Despite this, almost all eukaryotic species reproduce sexually
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4. Asexual reproduction Sexual reproduction Female Generation 1 Female
Figure
Asexual reproduction
Sexual reproduction
Female
Generation 1
Female
Figure 46.3 The “reproductive handicap” of sex.

5. Asexual reproduction Sexual reproduction Female Generation 1 Female
Figure
Asexual reproduction
Sexual reproduction
Female
Generation 1
Female
Generation 2
Male
Figure 46.3 The “reproductive handicap” of sex.

6. Asexual reproduction Sexual reproduction Female Generation 1 Female
Figure
Asexual reproduction
Sexual reproduction
Female
Generation 1
Female
Generation 2
Male
Generation 3
Figure 46.3 The “reproductive handicap” of sex.

7. Asexual reproduction Sexual reproduction Female Generation 1 Female
Figure
Asexual reproduction
Sexual reproduction
Female
Generation 1
Female
Generation 2
Male
Generation 3
Figure 46.3 The “reproductive handicap” of sex.
Generation 4

8. Introduction
Reproduction is not essential to the survival of the individual
Reproduction is vital to the survival of a species
In humans, the reproductive system produces, stores, nourishes, and releases sex cells known as gametes
Gametes come together to form the zygote, or fertilized egg
In males, gametes are formed in the testes and in females they are formed in the ovaries

9. Intro cont.
During the 7th week of embryonic development, testes produce hormones called androgens and ovaries produce hormones called estrogens that lead to the development of the respective reproductive organs
Neither testes nor ovaries are capable of producing Active Reproductive Cells until Puberty
Period of rapid growth and sexual maturation when reproductive organs become fully functional
Occurs between the ages of 9 & 15, usually 1 yr earlier in females
Begins with a change in the hypothalamus that instructs the pituitary gland to increase the levels of two hormones
Follicle Stimulating Hormone (FSH)
Luteinizing Hormone (LH)

10. Male Reproductive Anatomy
The male’s external reproductive organs are the scrotum and penis
Internal organs are the gonads, which produce sperm and hormones, and accessory glands

11. Seminal vesicle (behind bladder)
Figure 46.11
Seminal vesicle (behind bladder)
(Urinary bladder)
Prostate gland
Bulbourethral gland
Urethra
Erectile tissue of penis
Scrotum
Vas deferens
Epididymis
Testis
(Urinary bladder)
Seminal vesicle
(Urinary duct)
Figure Reproductive anatomy of the human male.
(Rectum)
(Pubic bone)
Vas deferens
Erectile tissue
Ejaculatory duct
Prostate gland
Urethra
Penis
Bulbourethral gland
Vas deferens
Glans
Epididymis
Testis
Prepuce
Scrotum

12. Male Reproductive Organs
1. Bladder 2. Vas deferens 3. Corpus Cavernosum
4. Corpus Spongiosum 5. Urethra 6. Glans penis
7. Prepuce 8. Testes 9. Epididymis
10. Bulbourethral gland 11. Prostate 12. Seminal Vesicle
13. Rectum 14. Ejaculatory Duct

13. Testes
The male gonads, or testes, consist of highly coiled tubes surrounded by connective tissue
Sperm form in these seminiferous tubules
Leydig cells produce hormones and are scattered between the tubules
Production of normal sperm cannot occur at the body temperatures of most mammals
What structure has nature developed to remedy this?
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14. The testes of many mammals are held outside the abdominal cavity in the scrotum, where the temperature is lower than in the abdominal cavity
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15. Male Reproductive System
Testosterone
FSH and LH stimulate the testes to make testosterone
Testosterone is the principle male sex hormone
It produces secondary sex characteristics that appear at puberty
Voice deepens
Facial hair
Body hair
Muscle development
FSH and Testosterone stimulate the development of sperm
When large numbers of sperm have been produced, the process of puberty is complete and the reproductive system is fully functional

16. Male Reproductive Cells
Sperm
Formed through meiosis – reduces the # of chromosomes to 23
Consists of 3 main parts
Head – contains the nucleus and enzymes that help penetrate the egg
Mid piece – contains mitochondria to provide energy to reach the egg
Tail – consists of a single, powerful flagellum that propels the sperm

17. Accessory Glands
Semen is composed of sperm plus secretions from three sets of accessory glands
The two seminal vesicles contribute about 60% of the total volume of semen
The prostate gland secretes its products directly into the urethra through several small ducts
The bulbourethral glands secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra
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18. Path of sperm Sperm travels from the testes to the epididymus
Matures and develops tail
Storage of sperm
Some sperm leave and enter the vas deferens
Duct that extends from the epididymus and wraps around the bladder and merges with the urethra
In the urethra, sperm mix with fluids from the 3 glands: Seminal Vesicles, Bulbouretheral gland, and the Prostate gland – this mixture is called semen
Semen contains fructose to provide energy and alkaline fluids to neutralize the acidity of the vagina
Semen also contains prostaglandins which stimulate smooth muscle contractions in the female reproductive system

19. Path cont
Sperm exits the body through the urethra – tube that leads out of the body through the penis
Sperm are ejected from the body by smooth muscle contractions in the vas deferens – this process is called ejaculation
Controlled by the autonomic nervous system
million sperm are released in a single ejaculation
Most are killed by the acidity of the vagina

20. Female Reproductive Anatomy
The female external reproductive structures include the clitoris and two sets of labia
The internal organs are a pair of gonads and a system of ducts and chambers that carry gametes and house the embryo and fetus
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21. Major vestibular (Bartholin’s) gland Labia minora Labia majora
Figure 46.10
Oviduct
Ovary
Uterus
(Urinary bladder)
(Pubic bone)
(Rectum)
Urethra
Cervix
Body
Vagina
Glans
Clitoris
Prepuce
Major vestibular (Bartholin’s) gland
Labia minora
Labia majora
Vaginal opening
Oviduct
Ovaries
Figure Reproductive anatomy of the human female.
Follicles
Corpus luteum
Uterus
Uterine wall
Endometrium
Cervix
Vagina

22. Female Reproductive System
Ovaries
Primary organ
Located in the lower abdomen
Usually produce one egg, or ovum, per month
Produce the principle sex hormone of females – estrogen
Estrogen
FSH and LH stimulate the ovary at puberty to release this hormone
Produces secondary sex characteristics
Enlargement of breasts
Widening of hips
Growth of body hair

23. Female Reproductive Cells
Ovum (egg)
Each ovary contains about 400,000 primary follicles, which are immature eggs (oocyte)
Some follicles will mature and become eggs
Other follicles prepare an egg to be released into the reproductive system where it can be fertilized
Fewer than 500 ova (eggs) are released in a lifetime
Ovulation is when an ovum matures and is released into the reproductive system
Begins at puberty and continues until a woman reaches her late 40’s – menopause
Follicle development ceases
Without follicles, ovaries cannot secrete enough estrogen and progesterone to continue menstrual cycle

24. Path of an Ovum
Once the egg has matured in the ovary, it is ruptured into the fallopian tubes
Provide a path from ovary to uterus
Ovum is moved by cilia that line the walls
Fertilization must occur in the fallopian tubes within 48 hours of being released – egg begins to breakdown after 48 hrs
If the egg is fertilized, it attaches to the uterus and develops into an embryo
If the egg is not fertilized, it signals the body to enter the 3rd stage of the menstrual cycle

25. Gametogenesis
Gametogenesis, the production of gametes, differs in male and female, reflecting the distinct structure and function of their gametes
Sperm are small and motile and must pass from male to female
Eggs are larger and carry out their function within the female
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26. Oogenesis, the development of a mature egg, is a prolonged process
Spermatogenesis, the development of sperm, is continuous and prolific (millions of sperm are produced per day; each sperm takes about 7 weeks to develop
Oogenesis, the development of a mature egg, is a prolonged process
Immature eggs form in the female embryo but do not complete their development until years or decades later
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27. Spermatogenesis differs from oogenesis in three ways
All four products of meiosis develop into sperm while only one of the four becomes an egg
Spermatogenesis occurs throughout adolescence and adulthood
Sperm are produced continuously without the prolonged interruptions in oogenesis
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28. Figure 46.12 Exploring: Human Gametogenesis
Figure 46.12a
Epididymis
Seminiferous tubule
Testis
Primordial germ cell in embryo
Cross section of seminiferous tubule
Mitotic divisions
Spermatogonial stem cell 2n
Mitotic divisions
Sertoli cell nucleus
Spermatogonium 2n
Mitotic divisions
Primary spermatocyte 2n
Meiosis I
Secondary spermatocyte n n
Figure Exploring: Human Gametogenesis
Meiosis II
Lumen of seminiferous tubule
Spermatids (two stages)
Early spermatid
Neck n n n n
Tail
Midpiece
Head
Differentiation (Sertoli cells provide nutrients)
Plasma membrane
Sperm cell n n
Acrosome n n
Nucleus
Mitochondria

29. Cross section of seminiferous tubule Secondary spermatocyte
Figure 46.12aa
Epididymis
Seminiferous tubule
Sertoli cell nucleus
Spermato- gonium
Primary spermatocyte
Testis
Cross section of seminiferous tubule
Secondary spermatocyte
Spermatids (two stages)
Figure Exploring: Human Gametogenesis
Sperm cell
Lumen of seminiferous tubule

30. Primordial germ cell in embryo Mitotic divisions
Figure 46.12ab
Primordial germ cell in embryo
Mitotic divisions
Spermatogonial stem cell 2n
Mitotic divisions
Spermatogonium 2n
Mitotic divisions
Primary spermatocyte 2n
Meiosis I
Secondary spermatocyte n n
Meiosis II
Figure Exploring: Human Gametogenesis
Early spermatid n n n n
Differentiation (Sertoli cells provide nutrients)
Sperm cell n n n n

31. Neck Tail Midpiece Head Plasma membrane Acrosome Nucleus Mitochondria
Figure 46.12ac
Neck
Tail
Midpiece
Head
Plasma membrane
Acrosome
Nucleus
Figure Exploring: Human Gametogenesis
Mitochondria

32. Menstrual Cycle Last About One Month
Normal cycle every 28 days
Called menstrual cycle because they are marked by 3-7 days of bleeding called menses.
Menstrual cycle can be described a number of ways:
Ovarian cycle- changes to follicles
Uterine cycle- changes to uterus

33. Ovarian Cycle Aided by the endocrine system
Includes the development of an egg and a series of changes to the uterus
Consists of 4 stages (about 28 days total)
Follicular Stage (about 12 to 14 days)
Egg matures
Uterus lining thickens in preparation for embryo
Ovulation (about 2 days)
Shortest phase
Release of ovum
Fertilization

34. Ovarian Cycle cont. Luteal phase (about 7 to 10 days)
Cells of the ruptured follicle grow and form a new structure called the corpus luteum
Corpus luteum secretes large amounts of progesterone and estrogen which causes the pituitary gland to stop producing FSH and LH
Progesterone causes the uterus to thicken even more in preparation for embryo
If no embryo arrives, corpus luteum produces less and less hormones – causes blood vessels in uterine lining to close and break
Cells of the lining do not have adequate blood supply and break loose – mixture cells and blood is called menstrual fluid
Menstruation (about 3 to 7 days)
Passage of menstrual fluid through the vagina and out of the body

35. Figure 46.12 Exploring: Human Gametogenesis
Figure 46.12b
Primary oocyte within follicle
Ovary
Growing follicle
Primordial germ cell
In embryo
Mitotic divisions 2n
Oogonium
Mitotic divisions
Primary oocyte (present at birth), arrested in prophase of meiosis I
Mature follicle 2n
Ruptured follicle
Completion of meiosis I and onset of meiosis II
First polar body n n
Secondary oocyte, arrested at metaphase of meiosis II
Ovulated secondary oocyte
Figure Exploring: Human Gametogenesis
Ovulation, sperm entry
Completion of meiosis II
Second polar body
Corpus luteum n
Fertilized egg n
Degenerating corpus luteum

36. Primary oocyte within follicle
Figure 46.12ba
Ovary
Ruptured follicle
Primary oocyte within follicle
Ovulated secondary oocyte
Growing follicle
Figure Exploring: Human Gametogenesis
Corpus luteum
Mature follicle
Degenerating corpus luteum

37. Uterine Cycle Endometrial lining goes through various changes.
Menses- beginning of follicular phases (bleeding)
Proliferative phase- endometrium begins to thicken to prepare for possible implantation
Secretory phase- after ovulation, corpus luteum converts thickened endometrium to secretory structure if pregnant. No pregnancy = sloughing of endometrium aka menses

38. Hormonal Control of the Female Reproductive Cycles
Ovarian and uterian cycle are under primary control of various hormones:
GnRH (Gonadotrophin Relasing Hormone) from the hypothalamus
FSH (Follicle Stimulating Hormone) and LH (Luteinizing hormone) from anterior pituitary
Esrogen, progesterone from ovary
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39. The Ovarian Cycle
The sequential release of GnRH then FSH and LH stimulates follicle growth
Follicle growth and an increase in the hormone estradiol characterize the follicular phase of the ovarian cycle
As the follicle matures, some follicles undergo atresia (hormonal cell death) to only allow 1 mature egg to survive)
The follicular phase ends at ovulation, and the secondary oocyte is released
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40. Following ovulation, the follicular tissue left behind transforms into the corpus luteum; this is the luteal phase
The corpus luteum disintegrates, and ovarian steroid hormones (Estrogen and Progesterone) decrease if an embryo was not implanted.
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41. Degenerating corpus luteum
Figure 46.13
(a)
Control by hypothalamus
Inhibited by combination of estradiol and progesterone
Hypothalamus 
Stimulated by high levels of estradiol 1
GnRH 
Anterior pituitary
Inhibited by low levels of estradiol  2
FSH LH
(b)
Pituitary gonadotropins in blood 6 LH
FSH 3
FSH and LH stimulate follicle to grow
LH surge triggers ovulation
(c)
Ovarian cycle 7 8
Growing follicle
Corpus luteum
Degenerating corpus luteum
Maturing follicle
Follicular phase
Ovulation
Luteal phase
Estradiol secreted by growing follicle in increasing amounts
Progesterone and estradiol secreted by corpus luteum 4
(d)
Ovarian hormones in blood
Peak causes LH surge (see ) 5 6
Figure The reproductive cycle of the human female. 10
Estradiol 9
Progesterone
Estradiol level very low
Progesterone and estra- diol promote thickening of endometrium
(e)
Uterine (menstrual) cycle
Endometrium
Menstrual flow phase
Proliferative phase
Secretory phase
Days 5 10 14 15 20 25 28

42. Control by hypothalamus
Figure 46.13a
(a)
Control by hypothalamus
Inhibited by combination of estradiol and progesterone
Hypothalamus 
Stimulated by high levels of estradiol  1
GnRH
Anterior pituitary
Inhibited by low levels of estradiol  2
FSH LH
Figure The reproductive cycle of the human female.

43. Degenerating corpus luteum
Figure 46.13b
(b)
Pituitary gonadotropins in blood 6 LH
FSH 3
FSH and LH stimulate follicle to grow
LH surge triggers ovulation
(c)
Ovarian cycle 7 8
Figure The reproductive cycle of the human female.
Corpus luteum
Degenerating corpus luteum
Growing follicle
Maturing follicle
Follicular phase
Ovulation
Luteal phase
Days 5 10 14 15 20 25 28

44. Estradiol secreted by growing follicle in increasing amounts
Figure 46.13c
Estradiol secreted by growing follicle in increasing amounts
Progesterone and estradiol secreted by corpus luteum 4
(d)
Ovarian hormones in blood
Peak causes LH surge (see ) 6 5 10 9
Estradiol
Progesterone
Estradiol level very low
Progesterone and estra- diol promote thickening of endometrium
(e)
Uterine (menstrual) cycle
Figure The reproductive cycle of the human female.
Endometrium
(e)
Menstrual flow phase
Proliferative phase
Secretory phase
Days 5 10 14 15 20 25 28

45. Degenerating corpus luteum
Figure 46.13
(a)
Control by hypothalamus
Inhibited by combination of estradiol and progesterone
Hypothalamus 
Stimulated by high levels of estradiol 1
GnRH 
Anterior pituitary
Inhibited by low levels of estradiol  2
FSH LH
(b)
Pituitary gonadotropins in blood 6 LH
FSH 3
FSH and LH stimulate follicle to grow
LH surge triggers ovulation
(c)
Ovarian cycle 7 8
Growing follicle
Corpus luteum
Degenerating corpus luteum
Maturing follicle
Follicular phase
Ovulation
Luteal phase
Estradiol secreted by growing follicle in increasing amounts
Progesterone and estradiol secreted by corpus luteum 4
(d)
Ovarian hormones in blood
Peak causes LH surge (see ) 5 6
Figure The reproductive cycle of the human female. 10
Estradiol 9
Progesterone
Estradiol level very low
Progesterone and estra- diol promote thickening of endometrium
(e)
Uterine (menstrual) cycle
Endometrium
Menstrual flow phase
Proliferative phase
Secretory phase
Days 5 10 14 15 20 25 28

46. Pregnancy
The presence of a developing embryo as a result of fertilization
Fertilization must occur in the upper 1/3 of the fallopian tube
Enzymes in the head of sperm help the sperm to penetrate the egg
When penetration occurs, the egg prevents the any further penetration
Egg and sperm nuclei fuse to form a diploid zygote
After fert. the cell undergoes a period of mitosis
This is called cleavage
The dividing mass of cells (morula) moves down the fallopian tube to the uterus
The morula continues to divide and becomes a blastocyst which attaches to the uterine lining

47. Embryonic Development
1st eight weeks of development
All major internal organs and external features appear
During 2nd week, the inner cell mass transforms into the embryonic disk and layers form within it
These layers become the 3 germ layers and give rise to all organ systems
Ectoderm – nervous system, portions of sensory organs, the epidermis, and the linings of the mouth and anus
Mesoderm – muscle and bone tissue, blood, blood and lymph vessels, internal reproductive organs, kidneys, and epithelial linings of body cavities
Endoderm – epithelial linings of the digestive tract, respiratory tract, urinary bladder, and urethra

48. Embryonic Development cont.
Also during the 2nd and 3rd weeks, the chorionic villi begins to develop from the trophoblast along with the yolk sac, amnion and allantois
Chorionic villi will become the chorion, a portion of which becomes the placenta – receives nutrients, oxygen, antibodies, and hormones from the mother as well as filters out wastes
Yolk sac is the first site of blood cell formation and stem cells for the immune system
Amnion holds amniotic fluid and provides cushioning
Allantois also forms blood cells and gives rise to umbilical arteries and veins.

49. Embryonic cont. Week 4 Weeks 5 – 8
Heart is beating, head and jaw appears and limb buds form
Weeks 5 – 8
All major body systems form
Embryo is now between 30 and 50 mm
At the end of the 8th week the embryo is now referred to as a fetus

50. Fetal Development
Begins at the end of the 8th week and lasts until birth
Growth is rapid and body proportions change considerably
Existing structures grow and mature and only a few new parts appear
Limbs grow to relative size and bones begin to ossify
During the 5th month ( weeks) the mother can feel the fetus move
In the final trimester, brain cells develop rapidly, organs mature, and the fetus greatly increases in size

51. Parturition Full term is between 30 and 40 weeks
As the placenta ages, less progesterone is produced (usually inhibits uterine contractions)
Decreasing levels of progesterone stimulate the synthesis of prostaglandins which initiate labor
Stretching uterine tissues stimulate the production of oxytocin from the posterior pituitary which initiate uterine contractions
As the fetal head stretches the cervix, a positive feedback mechanism results in greater uterine contractions and a greater release of oxytocin
This causes the abdominal muscles to contract and force the fetus through the birth canal

52. Parturition cont.
When the baby comes out (head first) it is still attached to the mother by the umbilical cord
The umbilical is cut and clamped leaving a scar – naval or belly button
Baby will begin to cough or cry to rid the fluid in the lungs – breathing begins almost immediately
In the final contractions, the placenta, amniotic sac, and uterine lining are expelled – after birth

53. Postnatal Milk production and secretion Neonatal period
After birth, prolactin stimulates the mammary glands in the breast to produce large quantities of milk
First milk, or colostrum, is rich in proteins and antibodies
Milk does not readily flow, but is triggered by the infant suckling at the breast
Breast milk is the best possible food for the baby
Neonatal period
Lasts for about 4 weeks after birth
Newborn must be able to live off fat reserves for 2-3 days until mother milk comes in
Newborn is very susceptible to dehydration because the kidneys are not yet fully function
Changes in circulation occur during the first few minutes but the foramen ovale may take up to year to close
Allows blood to enter the left atrium from the right atrium in the fetal heart - lung bypass