1. Highlights of Reproductive Physiology
From Marieb’s Human Anatomy and Physiology

2. Reproductive System Primary sex organs (gonads): testes and ovaries
Produce sex cells (gametes)
Secrete steroid sex hormones
Androgens (males)
Estrogens and progesterone (females)
Accessory reproductive organs: ducts, glands, and external genitalia

3. Reproductive System Sex hormones play roles in
Development and function of the reproductive organs
Sexual behavior and drives
Growth and development of many other organs and tissues

4. Seminiferous tubule (c) Interstitial cells Spermatogenic
cells in tubule
epithelium
Areolar
connective
tissue
Myoid
cells
Sperm
Figure 27.3c

5. Male Sexual Response Erection:
Parasympathetic reflex promotes release of nitric oxide (NO)
NO causes erectile tissue to fill with blood
Expansion of the corpora cavernosa
Compresses drainage veins and maintains engorgement
Corpus spongiosum keeps the urethra open
Impotence: the inability to attain erection

6. Male Sexual Response Ejaculation
Propulsion of semen from the male duct system
Sympathetic spinal reflex causes
Ducts and accessory glands to contract and empty their contents
Bladder sphincter muscle to constrict, preventing the expulsion of urine
Bulbospongiosus muscles to undergo a rapid series of contractions

7. Spermatogenesis Spermatic cells give rise to sperm Mitosis Meiosis
Spermatogonia form spermatocytes
Meiosis
Spermatocytes form spermatids
Spermiogenesis
Spermatids become sperm

8. Figure 27.7a

9. Spermatogonium
(stem cell)
Cytoplasm of adjacent
sustentacular cells
Sustentacular
cell nucleus
Basal lamina
Type A daughter cell
remains at basal lamina
as a stem cell
Type B daughter cell
Tight junction between
sustentacular cells
Primary
spermatocyte
Secondary
spermatocytes
Early
spermatids
Late spermatids
Cytoplasmic
bridge
Spermatozoa
Lumen of
seminifer-
ous tubule
(c) A portion of the seminiferous tublule wall, showing the spermato-
genic cells surrounded by sustentacular cells (colored gold)
Figure 27.7c

10. Basal lamina
Spermatogonium
(stem cell)
Type A daughter cell
remains at basal lamina
as a stem cell
Mitosis
Type B daughter cell
Growth
Enters meiosis I
and moves to
adluminal
compartment
Primary
spermatocyte
Meiosis I
completed
Secondary
spermatocytes
Meiosis II
Early
spermatids
Late spermatids
Spermatozoa
(b) Events of spermatogenesis,
showing the relative position
of various spermatogenic cells
Figure 27.7b

11. Role of Sustentacular Cells
Large supporting cells (Sertoli cells)
Extend through the wall of the tubule and surround developing cells
Provide nutrients and signals to dividing cells
Dispose of excess cytoplasm sloughed off during spermiogenesis
Secrete testicular fluid into lumen for transport of sperm

12. Role of Sustentacular Cells
Tight junctions divide the wall into two compartments
Basal compartment—spermatogonia and primary spermatocytes
Adluminal compartment—meiotically active cells and the tubule lumen

13. Hormonal Regulation of Male Reproductive Function
A sequence of hormonal regulatory events involving the hypothalamus, anterior pituitary gland, and the testes
The hypothalamic-pituitary-gonadal (HPG) axis

14. HPG Axis Hypothalamus releases gonadotropin-releasing hormone (GnRH)
GnRH stimulates the anterior pituitary to secrete FSH and LH
FSH causes sustentacular cells to release androgen-binding protein (ABP), which makes spermatogenic cell receptive to testosterone
LH stimulates interstitial cells to release testosterone

15. HPG Axis Testosterone is the final trigger for spermatogenesis
Feedback inhibition on the hypothalamus and pituitary results from
Rising levels of testosterone
Inhibin (released when sperm count is high)

16. GnRH Anterior Via portal pituitary blood Inhibin FSH LH Interstitial1
GnRH
Anterior
pituitary
Via portal
blood 8 7 2
Inhibin 2
FSH LH
Interstitial
cells 3 4 6
Testosterone
Somatic and
psychological
effects at
other body
sites
Sustentacular
cell
Spermatogenic
cells 5
Seminiferous
tubule
Stimulates
Inhibits
Figure 27.9

17. Mechanism and Effects of Testosterone Activity
Synthesized from cholesterol
Transformed to exert its effects on some target cells
Dihydrotestosterone (DHT) in the prostate
Estrogen in some neurons in the brain

18. Mechanism and Effects of Testosterone Activity
Prompts spermatogenesis
Targets all accessory organs; deficiency leads to atrophy
Has multiple anabolic effects throughout the body
Is the basis of the sex drive (libido) in males

19. Male Secondary Sex Characteristics
Features induced in the nonreproductive organs by male sex hormones (mainly testosterone)
Appearance of pubic, axillary, and facial hair
Enhanced growth of the chest and deepening of the voice
Skin thickens and becomes oily
Bones grow and increase in density
Skeletal muscles increase in size and mass

20. Female Physiology

21. Oogenesis Production of female gametes Begins in the fetal period
Oogonia (2n ovarian stem cells) multiply by mitosis and store nutrients
Primary oocytes develop in primordial follicles
Primary oocytes begin meiosis but stall in prophase I

22. Oogenesis
Each month after puberty, a few primary oocytes are activated
One is selected each month to resume meiosis I
Result is two haploid cells
Secondary oocyte
First polar body

23. Oogenesis The secondary oocyte arrests in metaphase II and is ovulated
If penetrated by sperm the second oocyte completes meiosis II, yielding
Ovum (the functional gamete)
Second polar body

24. Figure 27.17 Meiotic events Follicle development in ovary Before birth
Oogonium (stem cell)
Follicle cells
Mitosis
Oocyte
Primary oocyte
Primordial follicle
Growth
Infancy and
childhood
(ovary inactive)
Primary oocyte
(arrested in prophase I;
present at birth)
Primordial follicle
Each month from
puberty to
menopause
Primary follicle
Primary oocyte (still
arrested in prophase I)
Secondary follicle
Spindle
Vesicular (Graafian)
follicle
Meiosis I (completed
by one primary oocyte
each month in response
to LH surge)
Secondary oocyte
(arrested in
metaphase II)
First polar body
Ovulation
Meiosis II of polar
body (may or may
not occur)
Sperm
Ovulated secondary
oocyte
Meiosis II
completed
(only if
sperm
penetration
occurs)
In absence of
fertilization, ruptured
follicle becomes a
corpus luteum and
ultimately degenerates.
Polar bodies
(all polar bodies
degenerate)
Second
polar body
Ovum
Degenating
corpus luteum
Figure 27.17

25. Ovarian Cycle
Monthly series of events associated with the maturation of an egg
Two consecutive phases (in a 28-day cycle)
Follicular phase: period of follicle growth (days 1–14)
Ovulation occurs midcycle
Luteal phase: period of corpus luteum activity (days 14–28)

26. Follicular Phase Primordial follicle becomes primary follicle
The primordial follicle is activated
Squamouslike cells become cuboidal
Follicle enlarges to become a primary (1) follicle

27. Primordial follicles 1 Theca folliculi Primary oocyte Zona pellucida3 4 2
Primary oocyte 1
Zona pellucida
Antrum
Secondary
oocyte 5 1
Primordial
follicles 8 6
Secondary oocyte 7
Corona radiata
Figure (1 of 7)

28. Primary follicle 2 Theca folliculi Primary oocyte Zona pellucida3 4 2
Primary oocyte 1
Zona pellucida
Antrum
Secondary
oocyte 5
Primary
follicle 2 8 6
Secondary oocyte
Corona radiata 7
Figure (2 of 7)

29. Follicular Phase Primary follicle becomes a secondary follicle
Stratified epithelium (granulosa cells) forms around oocyte
Granulosa cells and oocyte guide one another’s development

30. Follicular Phase Secondary follicle becomes a late secondary follicle
Connective tissue (theca folliculi) and granulosa cells cooperate to produce estrogens
Zona pellucida forms around the oocyte
Fluid begins to accumulate

31. Secondary follicle 3 Theca folliculi Primary oocyte Zona pellucida4 2
Primary oocyte 1
Zona pellucida
Antrum
Secondary
oocyte 5 3
Secondary
follicle 8 6
Secondary oocyte 7
Corona radiata
Figure (3 of 7)

32. Theca folliculi Primary oocyte Zona pellucida Antrum Secondary oocyte3 4 2
Primary oocyte 1
Zona pellucida
Antrum
Secondary
oocyte 5 8 6
Secondary oocyte 4
Late secondary
follicle 7
Corona radiata
Figure (4 of 7)

33. Follicular Phase Late secondary follicle becomes a vesicular follicle
Antrum forms and expands to isolate the oocyte with its corona radiata on a stalk
Vesicular follicle bulges from the external surface of the ovary
The primary oocyte completes meiosis I

34. Ovulation
Ovary wall ruptures and expels the secondary oocyte with its corona radiata
Mittelschmerz: twinge of pain sometimes felt at ovulation
1–2% of ovulations release more than one secondary oocyte, which, if fertilized, results in fraternal twins

35. Theca folliculi Primary oocyte Zona pellucida Antrum Secondary oocyte3 4 2
Primary oocyte 1
Zona pellucida
Antrum
Secondary
oocyte
Mature vesicular
follicle carries out
meiosis I; ready to
be ovulated 5 5 8 6
Secondary oocyte
Corona radiata 7
Figure (5 of 7)

36. Follicle ruptures; secondary oocyte ovulated Theca folliculi3 4 2
Primary oocyte 1
Zona pellucida
Antrum
Secondary
oocyte 5 6
Follicle ruptures;
secondary oocyte
ovulated 8 6
Secondary oocyte 7
Corona radiata
Figure (6 of 7)

37. Luteal Phase Ruptured follicle collapses
Granulosa cells and internal thecal cells form corpus luteum
Corpus luteum secretes progesterone and estrogen

38. Luteal Phase
If no pregnancy, the corpus luteum degenerates into a corpus albicans in 10 days
If pregnancy occurs, corpus luteum produces hormones until the placenta takes over at about 3 months

39. Corpus luteum (forms from ruptured follicle) Theca folliculi3 4 2
Primary oocyte 1
Zona pellucida
Antrum
Secondary
oocyte 5 7
Corpus luteum
(forms from
ruptured follicle) 8 6
Secondary oocyte 7
Corona radiata
Figure (7 of 7)

40. Establishing the Ovarian Cycle
During childhood, ovaries grow and secrete small amounts of estrogens that inhibit the hypothalamic release of GnRH
As puberty nears, GnRH is released; FSH and LH are released by the pituitary, and act on the ovaries
These events continue until an adult cyclic pattern is achieved and menarche occurs

41. Establishing the Ovarian Cycle
During childhood, until puberty
Ovaries secrete small amounts of estrogens
Estrogen inhibits release of GnRH

42. Establishing the Ovarian Cycle
At puberty
Leptin from adipose tissue decreases the estrogen inhibition
GnRH, FSH, and LH are released
In about four years, an adult cyclic pattern is achieved and menarche occurs

43. Hormonal Interactions During a 28-Day Ovarian Cycle
Day 1: GnRH  release of FSH and LH
FSH and LH  growth of several follicles, and estrogen release
 estrogen levels
Inhibit the release of FSH and LH
Stimulate synthesis and storage of FSH and LH
Enhance further estrogen output

44. Hormonal Interactions During a 28-Day Ovarian Cycle
Estrogen output by the vesicular follicle increases
High estrogen levels have a positive feedback effect on the pituitary at midcycle
Sudden LH surge at day 14

45. Hormonal Interactions During a 28-Day Ovarian Cycle
Effects of LH surge
Completion of meiosis I (secondary oocyte continues on to metaphase II)
Triggers ovulation
Transforms ruptured follicle into corpus luteum

46. Hormonal Interactions During a 28-Day Ovarian Cycle
Functions of corpus luteum
Produces inhibin, progesterone, and estrogen
These hormones inhibit FSH and LH release
Declining LH and FSH ends luteal activity and inhibits follicle development

47. Hormonal Interactions During a 28-Day Ovarian Cycle
Days 26–28: corpus luteum degenerates and ovarian hormone levels drop sharply
Ends the blockade of FSH and LH
The cycle starts anew

48. Early and midfollicular phases
Hypothalamus
Hypothalamus 5
GnRH
Positive
feedback exerted
by large in
estrogen
output. 4 8
Travels via
portal blood 1
Anterior pituitary 1 5
Progesterone
Estrogen
Inhibin
LH surge
FSH LH
Ruptured
follicle 6 2 2 8
Slightly
elevated
estrogen
and rising
inhibin
levels. 3 7
Thecal
cells
Granulosa
cells
Androgens
Corpus luteum
Mature follicle
Ovulated
secondary
oocyte
Convert
androgens to
estrogens
Inhibin 2
Late follicular and
luteal phases
Early and midfollicular phases
Figure 27.19

49. (a) Fluctuation of gonadotropin levels: Fluctuating LH
FSH
(a) Fluctuation of gonadotropin levels: Fluctuating
levels of pituitary gonadotropins (follicle-stimulating
hormone and luteinizing hormone) in the blood
regulate the events of the ovarian cycle.
Figure 27.20a

50. Primary follicle Vesicular follicle Corpus luteum Degenerating
Secondary
follicle
Ovulation
Follicular
phase
Ovulation
(Day 14)
Luteal
phase
(b) Ovarian cycle: Structural changes in the ovarian
follicles during the ovarian cycle are correlated with
(d) changes in the endometrium of the uterus during
the uterine cycle.
Figure 27.20b

51. Uterine (Menstrual) Cycle
Cyclic changes in endometrium in response to ovarian hormones
Three phases
Days 1–5: menstrual phase
Days 6–14: proliferative (preovulatory) phase
Days 15–28: secretory (postovulatory) phase (constant 14-day length)

52. Uterine Cycle Menstrual phase
Ovarian hormones are at their lowest levels
Gonadotropins are beginning to rise
Stratum functionalis is shed and the menstrual flow occurs

53. Uterine Cycle Proliferative phase
Estrogen levels prompt generation of new functional layer and increased synthesis of progesterone receptors in endometrium
Glands enlarge and spiral arteries increase in number

54. Uterine Cycle Secretory phase Progesterone levels prompt
Further development of endometrium
Glandular secretion of glycogen
Formation of the cervical mucus plug

55. (c) Fluctuation of ovarian hormone levels:
Estrogens
Progesterone
(c) Fluctuation of ovarian hormone levels:
Fluctuating levels of ovarian hormones (estrogens
and progesterone) cause the endometrial changes
of the uterine cycle. The high estrogen levels are
also responsible for the LH/FSH surge in (a).
Figure 27.20c

56. (d) The three phases of the uterine cycle:
Endometrial
glands
Blood vessels
Menstrual
flow
Functional layer
Basal layer
Days
Menstrual
phase
Proliferative
phase
Secretory
phase
(d) The three phases of the uterine cycle:
• Menstrual: Shedding of the functional layer of the
endometrium.
• Proliferative: Rebuilding of the functional layer of
the endometrium.
• Secretory: Begins immediately after ovulation.
Enrichment of the blood supply and glandular secretion of
nutrients prepare the endometrium to receive an embryo.
Both the menstrual and proliferative phases occur before ovulation, and
together they correspond to the follicular phase of the ovarian cycle. The
secretory phase corresponds in time to the luteal phase of the ovarian cycle.
Figure 27.20d

57. Uterine Cycle If fertilization does not occur
Corpus luteum degenerates
Progesterone levels fall
Spiral arteries kink and spasm
Endometrial cells begin to die
Spiral arteries constrict again, then relax and open wide
Rush of blood fragments weakened capillary beds and the functional layer sloughs

58. Effects of Estrogens
Promote oogenesis and follicle growth in the ovary
Exert anabolic effects on the female reproductive tract
Support the rapid but short-lived growth spurt at puberty

59. Effects of Estrogens Induce secondary sex characteristics
Growth of the breasts
Increased deposit of subcutaneous fat (hips and breasts)
Widening and lightening of the pelvis

60. Effects of Estrogens Metabolic effects
Maintain low total blood cholesterol and high HDL levels
Facilitates calcium uptake

61. Effects of Progesterone
Progesterone works with estrogen to establish and regulate the uterine cycle
Effects of placental progesterone during pregnancy
Inhibits uterine motility
Helps prepare the breasts for lactation

62. Female Sexual Response
Initiated by touch and psychological stimuli
The clitoris, vaginal mucosa, and breasts engorge with blood
Vestibular gland secretions lubricate the vestibule
Orgasm is accompanied by muscle tension, increase in pulse rate and blood pressure, and rhythmic contractions of the uterus

63. Female Sexual Response
Females do not have a refractory period after orgasm and can experience multiple orgasms in a single sexual experience
Orgasm is not essential for conception