1. The Reproductive System: Part B27
The Reproductive System: Part B

2. 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

3. 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

4. Testosterone is the final trigger for spermatogenesis
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)

5. 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

6. 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

7. 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

8. 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

9. Female Reproductive Anatomy
Ovaries: female gonads
Produce female gametes (ova)
Secrete female sex hormones (estrogen and progesterone)
Accessory ducts include
Uterine tubes
Uterus
Vagina

10. Female Reproductive Anatomy
Internal genitalia
Ovaries
Uterine tubes
Uterus
Vagina
External genitalia
The external sex organs

11. Suspensory ligament of ovary Infundibulum Uterine tube Ovary Fimbriae
Peritoneum
Uterus
Uterosacral
ligament
Round ligament
Vesicouterine
pouch
Perimetrium
Rectouterine
pouch
Urinary bladder
Pubic symphysis
Rectum
Mons pubis
Posterior fornix
Cervix
Urethra
Anterior fornix
Clitoris
Vagina
External urethral
orifice
Anus
Hymen
Urogenital diaphragm
Labium minus
Greater vestibular
(Bartholin’s) gland
Labium majus
Figure 27.10

12. Held in place by several ligaments
Ovaries
Held in place by several ligaments
Ovarian ligament: anchors ovary medially to the uterus
Suspensory ligament: anchors ovary laterally to the pelvic wall
Mesovarium: suspends the ovary
Broad ligament: supports the uterine tubes, uterus, and vagina; also contains the suspensory ligament and the mesovarium

13. Uterine (fallopian) tube Uterine tube Ovarian blood vessels Fundus
Suspensory
ligament of ovary
Uterine (fallopian) tube
Uterine
tube
Ovarian blood
vessels
Fundus
of uterus
Lumen (cavity)
of uterus
Ampulla
Mesosalpinx
Ovary
Isthmus
Mesovarium
Infundibulum
Broad
ligament
Fimbriae
Mesometrium
Round ligament of uterus
Ovarian ligament
Endometrium
Body of uterus
Myometrium
Wall of uterus
Ureter
Uterine blood vessels
Perimetrium
Isthmus
Internal os
Uterosacral ligament
Cervical canal
Lateral cervical
(cardinal) ligament
External os
Vagina
Lateral fornix
Cervix
(a)
Figure 27.12a

14. Surrounded by a fibrous tunica albuginea Two poorly defined regions
Ovaries
Blood supply: ovarian arteries and the ovarian branch of the uterine artery
Surrounded by a fibrous tunica albuginea
Two poorly defined regions
Cortex: ovarian follicles
Medulla: large blood vessels and nerves

15. Ovaries Follicle Immature egg (oocyte) surrounded by
Follicle cells (one cell layer thick)
Granulosa cells (when more than one layer is present)

16. Several stages of development
Follicles
Several stages of development
Primordial follicle: squamouslike follicle cells + oocyte
Primary follicle: cuboidal or columnar follicle cells + oocyte
Secondary follicle: two or more layers of granulosa cells + oocyte
Late secondary follicle: contains fluid-filled space between granulosa cells; coalesces to form a central antrum

17. Vesicular (Graafian) follicle
Ovaries
Vesicular (Graafian) follicle
Fluid-filled antrum forms; follicle bulges from ovary surface
Ovulation
Ejection of the oocyte from the ripening follicle
Corpus luteum develops from ruptured follicle after ovulation

18. Late secondary follicle Degenerating corpus luteum (corpus albicans)
Tunica
albuginea
Oocyte
Granulosa cells
Late secondary follicle
Degenerating corpus
luteum (corpus
albicans)
Cortex
Mesovarium and
blood vessels
Germinal
epithelium
Vesicular
(Graafian)
follicle
Primary
follicles
Antrum
Oocyte
Ovarian
ligament
Zona
pellucida
Theca
folliculi
Medulla
Ovulated
oocyte
Corpus luteum
Developing
corpus luteum
Corona
radiata
(a) Diagrammatic view of an ovary sectioned to reveal the follicles in its interior
Figure 27.11a

19. Female Duct System
Uterine (fallopian) tubes or oviducts
Uterus
Vagina

20. Isthmus: constricted region where tube joins uterus
Uterine Tubes
Ampulla
Distal expansion with infundibulum near ovary
Usual site of fertilization
Ciliated fibriae of infundibulum create currents to move oocyte into uterine tube
Isthmus: constricted region where tube joins uterus

21. Uterine Tubes
Oocyte is carried along by peristalsis and ciliary action
Nonciliated cells nourish the oocyte and the sperm
Mesosalpinx: mesentery that supports the uterine tubes

22. Uterine (fallopian) tube Uterine tube Ovarian blood vessels Fundus
Suspensory
ligament of ovary
Uterine (fallopian) tube
Uterine
tube
Ovarian blood
vessels
Fundus
of uterus
Lumen (cavity)
of uterus
Ampulla
Mesosalpinx
Ovary
Isthmus
Mesovarium
Infundibulum
Broad
ligament
Fimbriae
Mesometrium
Round ligament of uterus
Ovarian ligament
Endometrium
Body of uterus
Myometrium
Wall of uterus
Ureter
Uterine blood vessels
Perimetrium
Isthmus
Internal os
Uterosacral ligament
Cervical canal
Lateral cervical
(cardinal) ligament
External os
Vagina
Lateral fornix
Cervix
(a)
Figure 27.12a

23. Uterus
Body: major portion
Fundus: rounded superior region
Isthmus: narrowed inferior region

24. Cervix: narrow neck, or outlet; projects into the vagina
Uterus
Cervix: narrow neck, or outlet; projects into the vagina
Cervical canal communicates with the
Vagina via the external os
Uterine body via the internal os
Cervical glands secrete mucus that blocks sperm entry except during midcycle

25. Supports of the Uterus
Mesometrium—lateral support: portion of the broad ligament
Lateral cervical (cardinal) ligaments: from the cervix and superior part of the vagina to the walls of the pelvis
Uterosacral ligaments secure uterus to the sacrum
Round ligaments bind to the anterior wall

26. Uterine (fallopian) tube Uterine tube Ovarian blood vessels Fundus
Suspensory
ligament of ovary
Uterine (fallopian) tube
Uterine
tube
Ovarian blood
vessels
Fundus
of uterus
Lumen (cavity)
of uterus
Ampulla
Mesosalpinx
Ovary
Isthmus
Mesovarium
Infundibulum
Broad
ligament
Fimbriae
Mesometrium
Round ligament of uterus
Ovarian ligament
Endometrium
Body of uterus
Myometrium
Wall of uterus
Ureter
Uterine blood vessels
Perimetrium
Isthmus
Internal os
Uterosacral ligament
Cervical canal
Lateral cervical
(cardinal) ligament
External os
Vagina
Lateral fornix
Cervix
(a)
Figure 27.12a

27. Sacs of peritoneum exist around the uterus
Peritoneal Pouches
Sacs of peritoneum exist around the uterus
Vesicouterine pouch is between bladder and uterus
Rectouterine pouch is between rectum and uterus

28. Uterine Wall Three layers
Perimetrium: serous layer (visceral peritoneum)
Myometrium: interlacing layers of smooth muscle
Endometrium: mucosal lining

29. Stratum functionalis (functional layer)
Endometrium
Stratum functionalis (functional layer)
Changes in response to ovarian hormone cycles
Is shed during menstruation
Stratum basalis (basal layer)
Forms new functionalis after menstruation
Unresponsive to ovarian hormones

30. Uterine Vascular Supply
Uterine arteries: arise from internal iliacs
Arcuate arteries: in the myometrium
Radial branches in the endometrium branch into
Spiral arteries  stratum functionalis
Straight arteries  stratum basalis
Spasms of spiral arteries leads to shedding of stratum functionalis

31. Spiral (coiled) artery
Lumen of uterus
Epithelium
Capillaries
Uterine glands
Venous sinusoids
Lamina propria of
connective tissue
Spiral (coiled) artery
Straight artery
Endometrial vein
Smooth muscle fibers
Radial artery
Arcuate artery
Uterine artery
(b)
Figure 27.13b

32. Vagina
Birth canal and organ of copulation
Extends between the bladder and the rectum from the cervix to the exterior
Urethra embedded in the anterior wall

33. Vaginal fornix: upper end of the vagina surrounding the cervix
Layers of wall
Fibroelastic adventitia
Smooth muscle muscularis
Stratified squamous mucosa with rugae
Mucosa near the vaginal orifice forms an incomplete partition called the hymen
Vaginal fornix: upper end of the vagina surrounding the cervix

34. Mons pubis Labia Prepuce majora of clitoris Labia minora Clitoris
(glans)
Urethral
orifice
Vestibule
Hymen
(ruptured)
Vaginal
orifice
Anus
Opening of the duct
of the greater
vestibular gland
(a)
Figure 27.14a

35. External Genitalia (Vulva or Pudendum)
Mons pubis: fatty area overlying pubic symphysis
Labia majora: hair-covered, fatty skin folds
Labia minora: skin folds lying within labia majora
Vestibule: recess between labia minora

36. Greater vestibular glands
External Genitalia
Greater vestibular glands
Homologous to the bulbourethral glands
Release mucus into the vestibule for lubrication

37. External Genitalia Clitoris Perineum
Erectile tissue hooded by a prepuce
Glans clitoris: exposed portion
Perineum
Diamond-shaped region between the pubic arch and coccyx
Bordered by the ischial tuberosities laterally

38. Inferior ramus of pubis
Clitoris
Labia minora
Labia majora
Inferior ramus of pubis
Pubic symphysis
Anus
Body of clitoris,
containing corpora
cavernosa
Clitoris (glans)
Crus of clitoris
Urethral orifice
Vaginal orifice
Greater
vestibular
gland
Bulb of
vestibule
(b)
Fourchette
Figure 27.14b

39. Mammary Glands
Modified sweat glands consisting of 15–25 lobes
Areola: pigmented skin surrounding the nipple
Suspensory ligaments: attach the breast to underlying muscle
Lobules within lobes contain glandular alveoli that produce milk

40. Mammary Glands
Milk  lactiferous ducts  lactiferous sinuses  open to the outside at the nipple

41. Pectoralis major muscle Suspensory ligament
First rib
Skin (cut)
Pectoralis major muscle
Suspensory ligament
Adipose tissue
Lobe
Areola
Nipple
Opening of
lactiferous duct
Lactiferous sinus
Lactiferous duct
Lobule containing
alveoli
Hypodermis
(superficial fascia)
Intercostal muscles
(a)
(b)
Figure 27.15

42. Usually arises from the epithelial cells of small ducts
Breast Cancer
Usually arises from the epithelial cells of small ducts
Risk factors include:
Early onset of menstruation and late menopause
No pregnancies or first pregnancy late in life
Family history of breast cancer
10% are due to hereditary defects, including mutations to the genes BRCA1 and BRCA2

43. Breast Cancer: Detection and Treatment
70% of women with breast cancer have no known risk factors
Early detection via self-examination and mammography
Treatment depends upon the characteristics of the lesion:
Radiation, chemotherapy, and surgery followed by irradiation and chemotherapy

44. (a) Mammogram procedure
Malignancy
(b) Film of normal breast
(c) Film of breast with tumor
Figure 27.16

45. Production of female gametes Begins in the fetal period
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

46. Each month after puberty, a few primary oocytes are activated
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

47. The secondary oocyte arrests in metaphase II and is ovulated
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

48. 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

49. Monthly series of events associated with the maturation of an egg
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)

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

51. 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)

52. 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)

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

54. 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

55. 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)

56. 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)

57. 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

58. 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

59. 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)

60. 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)

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

62. 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

63. 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)

64. 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