1. Human Reproduction

2. Anatomy of the human male
Main functions:
The production of sperm, the male gametes;
Spermatogenesis begins at puberty and continues until death;
Delivery of functional sperm to the female reproductive system

3. Anatomy of the human male

4. Anatomy of the human male
Production of Semen (a fluid comprised of):
Sperm, which are expelled through the ducts during ejaculation (≈1% of semen volume);
Glandular secretions that carry, nourish, and protect the sperm (mostly sugars & buffers)
Testes (plural):
Glands that produce sperm; located outside abdominal cavity within the scrotum
Scrotum ≡ (saclike pouch ≈ 1-3°C below normal body temperature - sperm can only form at this lower temperature)

5. How sperm leave the testes
Seminiferous tubules: carries/stores sperm in testes
Epididymis: a series of coiled ducts for maturation & temporary storage of sperm
Vas deferens: tube which carries sperm past connecting lubricating and support glands

6. How sperm leave the testes
Lubricating and support glands:
(a.) Seminal vesicles: secrete sugar-rich fluid that protects & nourishes sperm
(b.) Prostate gland: produces an alkaline fluid that neutralizes both urine in the male urethra and the acidic environment of the vagina
(c.) Bulbourethral glands: secrete fluids that lubricates the male urethra and allows easier coitus (intercourse)

7. How sperm leave the testes
Urethra: tube in the penis that transports semen out of the male’s body; also transports urine from the urinary bladder
Penis: copulatory organ; transient tumescence
Ejaculation: the release of semen through rhythmic contractions of smooth muscle in the Vas deferens

8. Anatomy of the human male

9. Anatomy of the human female
Main functions:
To produce the female gametes (ova);
To receive sperm;
To provide a suitable environment in which a fertilized ovum might develop during pregnancy

10. Anatomy of the human female

11. Anatomy of the human female
Ovaries:
Contain follicles that nurture ova;
Produces sex hormones;
Functional from puberty to menopause

12. Anatomy of the human female
Oviducts (Fallopian Tubes):
Convey (move) ova towards the uterus;
Muscular contractions & cilia draw ovum (egg) into oviduct;
Location for fertilization to occur

13. Anatomy of the human female
Uterus (womb):
Nourishes development of fertilized zygote;
Opens into the vagina at cervix
Vagina:
Receives the penis during coitus;
Forms the birth canal;
Multiple layers of expandable smooth muscle;
Potential, not defined, space

14. Anatomy of the human female

15. Anatomy of the human female

16. Puberty
Puberty: when secondary sexual characteristics develop and the potential for sexual reproduction is reached (sperm production or ovulation)
Changes are controlled by hormones that initiate development of secondary sex characteristics;
Primary sex characteristics are internal and external reproductive organs (genitalia)

17. Puberty in males (♂) Secondary sex characteristics:
Primary hormone: testosterone (testes);
2° Characteristics: increased hair (body, pubic, & facial), muscle development, deeper voice;
Spontaneous ejaculation

18. Puberty in females (♀) Secondary sex characteristics:
Primary hormone: estrogen (ovaries);
2° Characteristics: breast development, broadened pelvis, distribution of body fat; increased hair (body & pubic);
Menarche (onset of menstruation)

19. Reproductive hormones
Testosterone (♂ testes):
Sperm production & secondary sexual characteristics
Estrogen (♀ ovaries);
Ova production, preparing uterus for fertilized zygote & secondary sexual characteristics

20. Hormonal control of the testes
Stimuli from other areas in the brain
Androgens, (testosterone most important), stimulate sperm production
They also maintain homeostasis by a negative feedback mechanism that inhibits the secretion of FSH (follicle-stimulating hormone) and LH (luteinizing hormone)
Hypothalamus
Releasing hormone
Anterior pituitary
Negative feedback
FSH LH
Androgen production
Testis
Sperm production

21. Oogenesis: Production of ova
Oogenesis occurs within the ovaries
Lifetime supply of primary oocytes is present at birth that are ‘frozen’ in Prophase I
One (maybe more) primary oocyte matures each menstrual cycle to form a secondary oocyte + polar body
If the secondary oocyte is fertilized, it completes meiosis and becomes a haploid ovum + another polar body

22. Oogenesis: Production of ova

23. Ovum maturation in ovary
releases progesterone
maintains uterus lining
produces estrogen

24. Reproductive Cycle of the Adult Human Female
A cyclical pattern of hormone secretion and reproductive events.
Humans and many other primates have menstrual cycles.
If implantation of a fertilized zygote does not occur, the endometrium (lining of uterus) is shed through the cervix and vagina in the process called menstruation.

25. The Menstrual Cycle
The series of changes in the female reproductive system that includes producing an ovum and preparing the uterus for receiving it.
Once an ovum has been released during ovulation, the part of the follicle that remains in the ovary develops into a structure called the corpus luteum.
The menstrual cycle begins during puberty and continues for 30 to 40 years, until menopause.
At menopause, the female stops releasing ova and the secretion of female hormones decreases.

26. The Menstrual Cycle
Divided into three phases: the flow phase, the follicular phase, and the luteal phase.
The timing of each phase of the menstrual cycle correlates with hormone output from the pituitary gland, changes in the ovaries, and changes in the uterus.

27. Menstrual cycle Controlled by a complex interaction of 4 hormones:LH
FSH
Controlled by a complex interaction of 4 hormones:
follicle stimulating hormone (FSH);
luteinizing hormone (LH);
estrogen;
progesterone
ovulation = egg release
egg development
corpus luteum
estrogen
progesterone
lining of uterus
Days 7 14 21 28

28. Menstrual cycle: Flow phase
Day 1 of the menstrual cycle (1st phase) is the day menstrual flow begins.
The shedding of blood, fluid, mucus, and epithelial cells that make up the endometrium (the internal lining of the uterus) begins.
Contractions of the uterine muscles help expel the uterine lining and can cause discomfort in some females.
The level of FSH in the blood begins to rise, and a follicle in one of the ovaries begins to mature as meiosis of the prophase I cell proceeds.

29. Menstrual cycle: Follicular phase
Follicular (2nd) phase lasts from about day 6 to day 14.
As the follicle containing a primary oocyte continues to develop, it secretes estrogen, which stimulates the repair of the endometrial lining of the uterus.
Day 14 ovulation occurs:
Ovulation ≡ follicle enlarges and ruptures ovary wall; ovum is released to oviduct.
Mittelschmerz: ovulation pain

30. Menstrual cycle: Luteal phase
Luteal (3rd) phase begins after ovulation (≈ day 15).
Progesterone increases the blood supply of the endometrium.
These changes correspond to the arrival of a fertilized ovum (zygote).
If the ovum is not fertilized, the rising levels of progesterone and estrogen from the corpus luteum cause the hypothalamus to inhibit the release of FSH and LH.

31. Menstrual cycle: Luteal phase
Without fertilization, the corpus luteum degenerates and stops secreting progesterone or estrogen.
As hormone levels drop, the thick lining of the uterus begins to shed.
If fertilization occurs the endometrium begins secreting a fluid rich in nutrients for the embryo.

32. Female reproductive cycle
Feedback
egg matures &
is released (ovulation)
builds up uterus lining
estrogen
ovary
corpus luteum
progesterone
FSH & LH
fertilized egg (zygote)
maintains uterus lining
HCG
yes
pituitary gland
corpus luteum
pregnancy
GnRH no
progesterone
corpus luteum breaks down
progesterone drops
menstruation
maintains uterus lining
hypothalamus

33. Female hormones FSH & LH released from pituitary gland;
stimulates ova development & hormone release;
peak release = release of ova (ovulation)

34. Female hormones Estrogen
released from ovary cells around developing ova;
stimulates growth of lining of uterus;
decreasing levels initiate menstruation

35. Female hormones Progesterone released from corpus luteum in ovaries
stimulates blood supply to lining of uterus;
decreased levels sustains menstruation

36. Hormonal coordination of the menstrual and ovarian cycles
FSH (follicle stimulating hormone) produced by pituitary gland stimulates development of follicle
LH (luteinizing hormone) stimulates the development of the corpus luteum; stimulates ovulation

37. Hormonal coordination of the menstrual and ovarian cycles
Estrogen: secreted by ovaries, stimulates development of uterine lining before implantation
Progesterone: secreted by corpus luteum, maintains uterine lining during pregnancy

38. Fertilization
Fertilization is the union of a sperm and an ovum to form a diploid zygote.
Fertilization results in a zygote and triggers embryonic development.
Occurs normally inside of fallopian tube (oviduct).
Fertilization is NOT pregnancy!
(PATHWAY) Tens of millions of sperm enter the vagina  cervix  uterus  oviducts (fertilization)
sperm + ovum zygote
23(n) + 23(n)  46(2n)

39. Fertilization
Only one of the many millions of sperm entering the vagina will penetrate this human ovum to initiate fertilization

40. Fertilization
The shape of a human sperm cell is adapted to its function
Sperm cell is enzymes, DNA & mitochondria!

41. Multiple Fertilizations
If two (or more) ova are released in the same cycle and fertilized  fraternal siblings (different DNA)
If one ova is fertilized and mitotically divides into two (or more) separate zygotes  identical siblings (same DNA)

42. Fertilization

43. Implantation
Implantation: The fertilized zygote implants into thickened uterine lining and the embryo starts to secrete the hormone human chorionic gonadotropin (HCG) (the hormone used for pregnancy tests)
HCG keeps the corpus luteum functional and continuing to secrete progesterone.
By the third or fourth month, the placenta takes over for the corpus luteum, secreting enough estrogen and progesterone to maintain the pregnancy.
Implantation = Pregnancy!

44. Embryonic Development
Development: series of orderly, precise steps that transform a zygote into a multicellular embryo
Embryo ≡ early development stages of a multicellular organism
Includes:
1. cell division (mitotic)
2. cell growth
3. cell differentiation ≡ altering of unspecialized mitotic embryonic cells into specialized cells, tissues,& organs

45. Early Embryonic Development
Cleavage is the first major phase of embryonic development
It is the rapid succession of cell divisions (Mitotic)
It creates a multicellular embryo from the zygote
NO growth
Embryonic growth cannot occur until implantation occurs
ZYGOTE
Blastocoel
Cross section of blastula
BLASTULA (hollow ball)

46. Early Embryonic Development
Stages:
Morula ≡ solid ball of cells
Blastula ≡ single layer of cells surrounding a fluid-filled cavity called the blastocoel
NO growth; still dividing original single cell mass
ZYGOTE
Blastocoel
Cross section of blastula
BLASTULA (hollow ball)

47. Embryonic Development
Gastrulation is the second major phase of embryonic development
The cells at one end of the blastula move inward

48. Embryonic Development
Organs start to form after gastrulation
Embryonic tissue layers begin to differentiate into specific tissues and organ systems

49. Embryonic Membranes Amnion ≡ fluid filled sac for protection
Chorion ≡ will form the embryo’s part of the placenta
Yolk sac ≡ produces first blood cells & germ cells
Chorion
Amnion
Allantois
Yolk sac

50. Embryonic Membranes
Allantois ≡ will form the umbilical cord (ropelike structure that attaches embryo to uterus)
Umbilical cord brings nutrients in/wastes out of fetus
Ties into hepatic artery & vein in fetus - bellybutton
Chorion
Amnion
Allantois
Yolk sac

51. The Placenta
Placenta ≡ A growing fetus exchanges nutrients, oxygen, and wastes with the mother through the placenta
Made of maternal and fetal tissues
Substances pass both ways, but blood does not mix

52. Placenta
Nutrients, wastes, & gasses diffuse across capillaries

53. Fetal Development Gestation is pregnancy
It begins at implantation and continues until parturition (birth)
Pregnancy in humans usually lasts about 280 days, calculated from the first day of the mother’s last menstrual period.
Embryonic development of essential organs occurs in early pregnancy.
The embryo may encounter risks from faults in its genes & from mother’s exposure to environmental factors.

54. Human fetal development is divided into equal trimesters
First trimester (0 to 3 months)
The most rapid changes occur during the first trimester (most developmentally important)10 weeks
eeks10 weeks
10 weeks
4 weeks
7 weeks
10 weeks

55. Human fetal development is divided into equal trimesters
Second trimester (4 to 6 months)
Increase in size of fetus
General refinement of human features
12 weeks

56. Human fetal development is divided into equal trimesters
The fetus spends much of the 2nd & 3rd trimesters just growing…
…and doing flip-turns & kicks inside amniotic sac
Week 20

57. Human fetal development is divided into equal trimesters
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

58. Human fetal development is divided into equal trimesters
Third trimester (7 to 9 months)
30 weeks
(7.5 months)

59. Human fetal development is divided into equal trimesters
32 weeks (8 months)
The fetus sleeps 90-95% of the day & sometimes experiences REM sleep, an indication of dreaming

60. Human fetal development is divided into equal trimesters
Third trimester
Growth and preparation for birth
Provides time for maternal body to prepare for birth
Nooo!!! I don’t want to go to Murdoch’s class!

61. Three stages of labor Dilation of the cervix is the first stage
Cervix starts at less than 1 cm dilation (open) and reaches full dilation at 10 cm
Longest stage of labor (6-12 hours or longer; maybe MUCH longer!)

62. Three stages of labor Expulsion is the second stage
Period from full dilation of the cervix to delivery of the infant
Uterine contractions occur every 2-3 minutes (positive feedback)

63. Three stages of labor Expulsion is the second stage
Mother feels urge to push down with her abdominal muscles
Infant is forced down and out of uterus and vagina within a period of about 20 minutes

64. Three stages of labor
The delivery of the placenta is the final stage of labor
Usually occurs within 15 minutes after the birth of the baby
Some placenta’s are saved and frozen as they are a source of stem cells

65. Labor & Birth: Positive Feedback

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

67. Lactation: the ‘mam’ in mammal
Lactation ≡ milk production
Lactation is another positive feedback system
Suckling stimulates the hypothalamus pituitary gland to release oxytocin
Oxytocin stimulates mammary glands to secrete milk
Continued suckling continues milk production
Yes, males have mammary glands too!

68. Growth and Aging Once a baby is born, growth and learning continue.
Human growth varies with age and is somewhat gender dependent.
Females develop earlier

69. An adult ages
As an adult ages, his or her body undergoes many distinct changes:
-Slower metabolism
-White hair
-Thinner bones
-Vision & hearing diminish