Reproductive System

1
Reproductive System

• Chapter 27

2
Male Reproductive System

• Anatomy
• Scrotum
• Testes
• Penis
• Duct system
• Accessory glands semen

3
Scrotum
Figure 27.2

• Maintains testicular temperature at 3oC lower
  than core temperature
• Surface area varies in response to external
  temperature

4
Testes
Figure 27.3a

• Primary reproductive organ of the male
• Produces sperm testosterone
• Testicular lobules contain coiled seminiferous
  tubules.
• Seminiferous tubules the location of sperm
  production
• Interstitial cells in the connective tissue
  around the seminiferous tubules produce
  testosterone

5
Penis

• Designed to deliver sperm into the female
  reproductive tract
• Penile root
• Penile shaft
• Glans penis

Figure 27.4
6
Penis

• Corpus spongiosum
• midline ventral surrounds urethra proximally
  forms the bulb of the penis distally forms glans
  penis
• Corpora cavernosa
• paired dorsal erectile bodies that terminate
  proximally in the crura (crus) of the penis that
  are anchored to the pubic arch

7
Duct system male

• Epididymus
• Vas deferens
• Urethra (three regions)
• Prostatic urethra
• Membranous urethra
• Penile urethra

8
Duct system male
Figure 27.3a

• Epididymus receives immature sperm from the rete
  testis as the sperm move through the epididymus
  (20 days) they become fully motile

9
Duct system Male
Figure 27.3a

• Ductus (vas) deferens from the epididymus merges
  with the
• Seminal vesicle duct to form the
• Ejaculatory duct which enters the
• Prostate empties into the urethra

10
Duct system male
Figure 27.1

• Urethra serves both urinary reproductive
  systems
• Three regions
• Prostatic urethra
• Membranous urethra
• Penile urethra

11
Accessory glands Seminal Vesicles
Figure 27.1

• on posterior bladder wall
• make alkaline, seminal fluid containing
  fructose, ascorbic acid, vesiculase (coagulating
  enzyme) prostaglandins
• Seminal fluid 2/3 of volume of semen

12
Accessory glands - Prostate gland
Figure 27.1

• Surrounds urethra
• Produces a milky, slightly acidic fluid
• citrate, multiple enzymes PSA (prostate
  specific antigen)
• Prostatic fluid 1/3 of semen volume

13
Accessory glands
Figure 27.1

• Bulbourethral glands
• Produce a thick clear mucous that neutralizes
  acidic urine

14
Semen

• Semen
• Milky white mixture of sperm accessory gland
  secretions
• Provides
• Nutrients for sperm
• Chemical protection / activation
• Acts as a transport medium for sperm

15
Male Sexual Response

• Erection enlargement stiffening of the penis
• Parasympathetic reflex
• Triggers local release of Nitric Oxide causing
• Arteriolar dilation increased blood flow to
  erectile tissues
• Expansion of erectile tissues interferes with
  veins that drain the system maintains erection

16
Male Sexual Response

• Ejaculation propulsion of semen through the duct
  system
• SNS discharge causes
• Contraction throughout the ductal system
• Contraction of bladder sphincter
• Contraction of the bulbospongiosus muscles of the
  penis

17
Male Sexual Response

• Refractory period After ejaculation there is a
  refractory period during which a male is unable
  to have another ejaculation (minutes ? hours)

18
Spermatogenesis

• Cell differentiation events that produces male
  gametes (spermatozoa)

19
Spermatogenesis

• Diploid (2n)
• having 2 of each chromosome type (n) human 2n46
• Haploid
• having 1 of each chromosome type human n 23
• body cells are diploid (2n)
• Gametes are haploid (n)
• When 2 gametes fuse at fertilzation, n n 2n
• diploidy restored

20
Comparison of Mitosis Meiosis
Figure 27.6

• Meiosis
• Two consecutive nuclear divisions producing
• Four haploid daughter cells

21
Meiotic Cell Division Meiosis I

• Meiosis
• Meiosis I separates homologous chromosomes into
  different cells (i.e. diploid ?
  haploid)
• cells still retain 2 copies of each gene

Figure 27.7
22
Meiotic Cell Division Meiosis II

• Meiosis
• Meiosis II separates chromatids into separate
  cells
• generates cells with only 1 copy of each gene

Figure 27.7
23
Spermatogenesis

• Occurs in the seminiferous tubules
• Spermatogonia form epithelial basal layer of
  cells
• Spermatogonia (sperm stem cell)
• Divide by mitosis until puberty forming a large
  population

24
Spermatogenesis

• At puberty mitotic divisions of spermatogonia
  form
• Two daughter cells with different functions
• Type A cells
• Type B cells

25
Spermatocytes to Spermatids

• Type A remains to maintain the spermatogonia
  stem cell
• Type B primary spermatocyte (2n)
• Pushed toward lumen
• Meiosis I forming secondary spermatocytes (n)
  which undergo
• Meiosis II forming 4 spermatids (immature sperm)

26
Spermatogenesis Spermatids to Sperm
Figure 27.9a

• Spermatogenesis (spermatids ? sperm) a
  streamlining process
• Sperm head (filled with DNA)
• Acrosome (filled with lysosomal enzymes)
• Midpiece (mitochondrial wrapped contractile
  filaments)
• Tail (flagellum)

27
Spermatogenesis

• Sertoli (Sustentacular) cells
• Divide seminiferous tubule into 2 compartments
• Isolate newly formed sperm from blood
• blood-testis barrier prevents formation of
  antibodies against sperm

28
Hormonal Regulation Male

• Brain-testicular axis
• Interactions between
• Hypothalamus
• Anterior pituitary
• Testes

29
Brain-testicular axis

• Hypothalamus ? Gonadotropin-Releasing Hormone
  (GnRH)
• GnRH?Anterior pituitary secretion of
• Leutinizing Hormone (LH a.k.a. Interstitial Cell
  Stimulating Hormone ICSH)
• Stimulates interstitial cells to produce
  testosterone
• Follicle Stimulating Hormone (FSH)
• allows spermatogenesis by making cells receptive
  to testosterone

30
Brain-testicular axis

• Testosterone acts locally as the trigger for
  spermatogenesis
• Testosterone inhibits
• Release of GnRH (hypothalamus)
• Release of gonadotropins (anterior pituitary)
• Inhibin is produced by Sertoli cells when sperm
  counts are high inhibits GnRH FSH release

31
Hormonal Regulation of Testicular Function

• Feedback inhibition on hypothalamus pituitary
  from
• Rising levels of testosterone
• Increased inhibin

Figure 27.10
32
Brain-testicular axis

• Perinatal FSH, LH testosterone levels
• Near pubertal levels to allow development of the
  male reproductive system
• After a few months of age the levels drop to low
  levels until onset of puberty

33
Testosterone mechanism effects

• Testosterone is synthesized from cholesterol
  exerts effects by activating specific genes
• Testosterone targets accessory organs (ducts,
  glands penis) causing them to grow to adult
  proportions

34
Testosterone mechanism effects

• Testosterone induces
• Secondary sex characteristics
• pubic axillary hair
• voice change
• facial hair
• thickening of the skin
• increased sebum production
• increase in bone muscle mass

35
Female Reproductive System
Figure 27.11

• Anatomy
• Ovaries
• Duct System
• Fallopian Tubes
• Uterus
• Vagina external genitalia

36
Ovaries
Figure 27.14a

• Ovaries primary female reproductive organ
• Ovaries produce the female
• Gamete (ova/egg)
• Sex hormones (estrogens progesterone)

37
Ovaries
Figure 27.14a

• Ovaries paired organ
• Found on either side of the uterus
• Held in place by ligaments

38
Ovaries
Figure 27.12

• Ovarian follicles within the ovary consist of an
• Oocyte (immature ovum) encased in one or more
  layers of cells
• Single layer follicle cells
• Multiple layers granulosa cells
• Follicles at different stages have different
  structures

39
Ovaries
Figure 27.12

• Follicle stages structures
• Primordial follicle single layer of follicle
  cells surrounding oocyte
• Primary follicle two or more layers of granulosa
  cells
• Secondary follicle fluid filled spaces appear
  within granulosa merge to form the vesicular
  follicle.

40
Ovaries
Figure 27.12

• Follicle stages (cont)
• Vesicular (Graafian) follicle bulges from the
  ovary surface will rupture at ovulation
  releasing the oocyte
• Corpus luteum follicle remnant after rupture
  that forms the glandular corpus luteum

41
Female Duct System
Figure 27.14a

• Fallopian tubes uterine tubes, oviducts
• Infundibulum open funnel shaped structure with
  finger-like projections (fimbriae) that drape
  over ovary
• Ampulla widened region arching over ovary (the
  usual site of fertilization)
• Isthmus narrowed region where tube enters upper
  region of uterus

42
Female Duct System - Uterus

• hollow, thick walled, pear shaped, muscular organ
  that receives, retains nourishes a fertilized
  ovum
• Uterine support comes from the mesometrium, the
  lateral cervical ligaments, the uterosacral
  ligaments the round ligaments

43
Female Duct System Uterine Wall

• Endometrium mucosal lining of columnar
  epithelium
• Myometrium muscular middle layer interlaced
  bundles of smooth muscle
• Perimetrium outer covering of visceral peritoneum

44
Female Duct System Uterine Wall

• endometrium is a dynamic layer of epithelium with
  two layers
• Stratum functionalis undergoes cyclic changes in
  response to ovarian hormones is shed during
  menstruation
• Stratum basalis deeper layer that forms a new
  stratum functionalis after menstruation

Figure 27.15
45
Vagina
Figure 27.14a

• female organ of copulation birth canal

46
Vagina
Figure 27.14a

• 3 layers
• Mucosa stratified squamous epithelium with rugae
  (ridges)
• Muscularis smooth muscle
• Adventitia fibroelastic connective tissue

47
Vagina
Figure 27.14a

• Environment
• In adults, vaginal pH is decreased
• Helps to prevent infection
• Also hostile to sperm
• In adolescents, vaginal pH is increased
• More alkaline environment presents an increased
  risk for Sexually Transmitted Disease

48
Vagina

• Proximal end of the vagina
• Surrounds the cervix of the uterus
• Forming a recess (fornix) around the cervix
• Distal end forms the vaginal orifice with mucosal
  hymen (in virginal females)

49
External Genitalia
Figure 27.16

• Mons pubis rounded fat pad overlying the pubic
  symphysis
• Labia
• Labia majora two fatty skin folds with hair
  (homologous to scrotum)
• Labia minora two smaller, hairless skin folds
  (homologous to the male ventral penis)

50
External Genitalia
Figure 27.16

• Vestibule the recess surrounded by the labia
  minora includes
• Urethral opening
• Vaginal orifice
• Vestibular gland orifices

51
External Genitalia

• Clitoris
• Small, protruding structure
• Composed of erectile tissue (penis homolog)
• Hooded by anterior folds of the labia minora
  (prepuce of clitoris)
• Perineum diamond shaped region from pubic arch
  to coccyx laterally to the ischial tuberosities

52
Oogenesis
Figure 27.20

• maturation process for the ovum (egg)
• Oogonia fetal stem cells (diploid) start meiosis
  to become primary oocytes.

53
Oogenesis
Figure 27.19
54
Oogenesis
Figure 27.19

• Two routes for secondary oocyte
• If fertilized - secondary oocyte expels second
  polar body (nonviable) rapidly completes
  Meiosis II
• If unfertilized - secondary oocyte deteriorates

55
The Ovarian Cycle

• 28 Days
• Follicular phase days 1-14
• Luteal phase days 14-28

56
Follicular phase
Figure 27.20

• Days 1 -14
• Primordial follicle matures to form a primary
  follicle
• Follicular cells proliferate forming granulosa
  cells which regulate / stimulate oocyte maturation

57
Follicular phase
Figure 27.20

• Days 1 -14 (cont)
• Connective tissue condenses around the follicle
  forming
• The theca folliculi theca granulosa cells
  produce estrogens
• Granulosa cells produce
• A transparent membrane (zona pelucida) around the
  oocyte
• Clear liquid forms the antrum (cavity) of the
  secondary follicle

58
Follicular phase
Figure 27.20

• Days 1 -14 (cont)
• Antrum expands until the oocyte is isolated on a
  stalk within the follicle
• Now 1in. in diameter the vesicular follicle
  bulges from the surface of the ovary the oocyte
  is surrounded by a capsule of granulosa cells
  (corona radiata)

59
Follicular phase
Figure 27.20

• Day 14
• Ovulation the vesicular follicle wall ruptures,
  expels the secondary oocyte with its corona
  radiata

60
Luteal phase
Figure 27.12
Figure 27.20

• Days 14-28
• The ruptured follicle collapses remaining theca
  granulosa cells enlarge form an endocrine
  gland the corpus luteum

61
Luteal phase
Figure 27.12
Figure 27.20

• Days 14-28 (cont)
• The corpus luteum secretes progesterone some
  estrogen
• If no fertilization occurs the corpus luteum
  degenerates to form the corpus albicans (scar)
• If fertilization occurs the corpus luteum
  persists until the placenta takes over hormone
  production (3 mos.)

62
Gonadotropins, Hormones, the Ovarian Uterine
Cycles
Figure 27.22a, b
63
Hormonal Regulation

• During puberty GnRH ( thus FSH/LH) production
  increases until the adult cycle is achieved
• First menses menarche

Figure 27.22a, b
64
Hormonal Interactions

• Day 1
• Day 1 GnRH levels rise stimulating anterior
  pituitary release of FSH LH
• FSH LH stimulate follicle growth maturation
• LH stimulates theca cells to produce androgens
  which diffuse into the follicle are converted
  to estrogens by granulosa cells

65
Feedback Mechanisms in Ovarian Function
Figure 27.21
66
Hormonal Interactions

• Rising estrogen levels provide negative feedback
  to the anterior pituitary
• Inhibiting release of FSH/LH but encouraging
  storage of FSH/LH
• Within the ovary estrogen intensifies the effect
  of FSH enhancing estrogen production

67
Hormonal Interactions

• As estrogen continues to rise it exerts a
  positive feedback on the adenohypophysis
  resulting in a burst of LH

Figure 27.21
68
Hormonal Interactions

• Day 14
• LH surge prompts maturation of the primary
  follicle to form the secondary oocyte triggers
  ovulation

Figure 27.21
69
Hormonal Interactions

• At ovulation, estrogen levels decline
• LH surge also transforms the ruptured follicle
  into a corpus luteum
• Stimulates production of progesterone estrogen

Figure 27.21
70
Hormonal Interactions

• Rising progesterone estrogen exert negative
  feedback of FSH/LH release

Figure 27.21
71
Feedback Mechanisms in Ovarian Function
Figure 27.21
72
Hormonal Interactions

• Day 27
• After the corpus luteum stops functioning the
  decline in hormone levels allows
• Day 1 Increased GnRH (FSH/LH)

73
Gonadotropins, Hormones, the Ovarian Uterine
Cycles
Figure 27.22c, d
74
The Uterine Cycle

• Days 1-5
• Menstrual phase uterus sheds stratum
  functionalis of endometrium.
• Hormone levels are at their lowest
• GnRH FSH begin to rise
• The functionalis layer detaches from the stratum
  basalis is passed through the vagina (3-5 days
  of bleeding)

75
The Uterine Cycle

• Days 6-14
• Proliferative phase Endometrium rebuilds itself.
  
• Estrogen induces progesterone receptors in the
  endometrial cells
• The proliferative phase ends with ovulation
  associated rise in LH

76
The Uterine Cycle

• Days 15-28
• Secretory phase endometrium is prepared for
  implantation of the embryo.
• Progesterone acts on the endometrium
• Spiral arteries enhance blood supply
• The functionalis is converted into a secretory
  mucosa (secretes glycogen)

77
The Uterine Cycle

• Days 15-28
• As progesterone levels rise, LH levels decline
• If fertilization has not occurred the
  progesterone level declines (corpus luteum
  degenerates) the endometrium degenerates.
• If fertilization has occurred Ch 28

78
Menstrual cycle

• Gonadotropins, Hormones, the Ovarian Uterine
  Cycles
• FSH, LH, Follicle, Uterus

Figure 27.22 a,b,c, d
79
Estrogen mechanism effects

• Estrogen induces
• Secondary sex characteristics
• Growth of the breasts
• Increased deposits of subcutaneous fat
• Widening lightening of the pelvis

80
Female sexual response

• Clitoris, vaginal mucosa breasts become
  engorged with blood
• Clitoral Nipple erection
• Increased vestibular gland activity lubricates
  the vestibule

81
Female orgasm

• No ejaculation
• Muscle tension increases throughout the body
• Pulse BP rise
• Uterus contracts rhythmically
• No refractory period

82
Sexually Transmitted Disease

• Gonnorrhea Neisseria gonnorrhea
• Invades the mucosa of the reproductive tracts
• Congenital ? blindness
• Male urethritis, painful urination
• Female variable symptoms may lead to PID
  (pelvic inflammatory disease) sterility

83
Sexually Transmitted Disease

• Syphilis Treponema pallidum
• Primary Initial presentation of chancre at the
  site of infection
• Painless, heals spontaneously
• Congenital ? death
• Secondary pink skin rash, fever joint pain
• Tertiary destructive lesions (gumma) in CNS,
  blood vessels, bone skin

84
Sexually Transmitted Disease

• Chlamydia Chlamydia trachomatis
• Congenital conjunctivitis ? blindness, pneumonia
• Male urethritis, testicular pain, urogenital
  inflammation, arthritis
• Female 80 no symptoms PID may lead to sterility

85
Final Freebie

• All somatic body cells diploid
• _______ogonia diploid
• Primary ___cyte diploid
• Secondary ___cyte haploid
• Gamete (Sperm/ova) haploid

86
Structure of Lactating Mammary Glands
Figure 27.17
87
Development of Internal Reproductive Organs
Figure 27.24
88
Development of Internal Reproductive Organs
Figure 27.24
89
Development of Internal Reproductive Organs
Figure 27.24
90
Development of Internal Reproductive Organs
Figure 27.24
91
Development of Internal Reproductive Organs
Figure 27.24
92
Development of External Genitalia Male
Figure 27.25a
93
Development of External Genitalia Male
Figure 27.25b
94
Development of External Genitalia Female
Figure 27.25a
95
Development of External Genitalia Female
Figure 27.5c
96
Development Aspects Descent of the Gonads
Figure 27.26a
97
Development Aspects Descent of the Gonads
Figure 27.26b
98
Development Aspects Descent of the Gonads
Figure 27.26c
99
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