TOPIC 12 Reproductive System

1
TOPIC 12 Reproductive System
Biology 221 Anatomy Physiology II

• Chapter 28
• pp. 1071-1107

E. Lathrop-Davis / E. Gorski / S. Kabrhel
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Male Anatomy Overview

• Consists of
• Testes
• Ducts
• epididymus
• ductus (vas) deferens
• ejaculatory duct
• urethra
• Penis
• Accessory glands
• seminal vesicles
• prostate
• bulblurethral (Cowpers)

http//www.msms.doe.k12.ms.us/biology/anatomy/repr
oductive/376a.gif
Fig. 28.1, p. 1071
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Male Testis

• Located in scrotum
• temperature regulation (keeps them at about 33oC)
• Structure of testis
• seminiferous tubules
• interstitial cells (cells of Leydig)
• rete testis

Fig. 28.3, p. 1073
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Male Testis Seminiferous Tubules

• Produce sperm
• Sustentacular (Sertoli) cells (5) support
  spermatocytes and spermatozoa, and produce
  inhibin (inhibits FSH/LH secretion)

http//www.usc.edu/hsc/dental/ghisto/rep/d_74.html
http//www.usc.edu/hsc/dental/ghisto/rep/d_74.html
5
Male Testis Interstitial Cells and Rete Testis

• Interstitial cells (between seminiferous tubules)
  produce testosterone (promotes sperm formation)
• Rete testis
• first collection area
• network of tubules on posterior side
• Lead to epididymus

http//www.usc.edu/hsc/dental/ghisto/rep/d_74.html
http//www.usc.edu/hsc/dental/ghisto/rep/d_75.html
Fig. 28.3, p. 1073
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Male Testis Coverings

• tunica vaginalis (TV) connective tissue,
  derived from peritoneum
• tunica albuginea (TA) fibrous capsule
• septa (S singular septum) extensions of
  tunica albuginea divide testis into sections

Fig. 28.3, p. 1073
http//www.usc.edu/hsc/dental/ghisto/rep/d_72.html
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Male Duct System

• Epididymis site of sperm maturation
• Ductus (vas) deferens carries sperm away from
  testis to ejaculatory duct
• Ejaculatory Duct extends from where ducts from
  seminal vesicles join ductus deferens to urethra

Fig. 28.1, p. 1071
http//www.msms.doe.k12.ms.us/biology/anatomy/repr
oductive/376a.gif
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Male Urethra

• Prostatic urethra runs through prostate gland
• Membranous urethra runs from prostate to penis
• Penile urethra runs through penis

Fig. 28.4, p. 1075
http//www.nku.edu/dempseyd/REPRODUCTION_2.htm
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Male Penis

• Designed to deliver sperm into vagina of female
• Erectile tissues
• Corpora cavernosa (CC)
• Corpus spongiosum (CS) surrounds urethra

Fig. 28.4, p. 1075
http//wbiomed.curtin.edu.ou/teach/humanbiol/hb134
/134hist/penis.htm
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Male Accessory Glands Semen

• Semen sperm plus products of the accessory
  glands that support and nourish the sperm sperm
• Glands (overview)
• Seminal vesicles (SV)
• Prostate gland
• Bulbourethral (Cowpers) glands

Fig. 28.1, p. 1071
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Male Accessory Glands Seminal Vesicles

• produce about 60 of all semen
• alkaline fluid neutralizes acidity of vagina
• fructose nourishes sperm

Fig. 28.1, p. 1071
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Male Accessory Glands Prostate

• encircles urethra below bladder
• produces about 30 of semen
• products play a role in activating and protecting
  sperm
• citrate nourishes sperm

http//www.usc.edu/hsc/dental/ghisto/rep/d_96.html
Fig. 28.1, p. 1071
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Male Accessory GlandBulbourethral Glands

• Lie near base of penis
• Produce mucus that neutralizes acidity of traces
  of urine in urethra

Fig. 28.1, p. 1071
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Male Reproductive Physiology Sperm Production
Overview

• Sperm (and ova) are produce by meiotic cell
  division
• Sperm production involves two stages
• Spermatogenesis in which diploid cells divide
  by meiotic cell division to yield haploid gametes
• Spermiogenesis maturation of spermatids into
  functional spermatozoa (sperm)

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Comparison of Mitosis Meiosis
Meiosis
Mitosis
Fig. 28.6, p. 1078
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Spermatogenesis

• Spermatogonia divide by mitosis to produce
• type A daughter cells that produce more
  spermatogonia (sperm production continues
  throughout mans life)
• type B daughter cells that spermatocytes (type B
  cell becomes primary spermatocyte)

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Spermatogenesis

• Spermatocytes divide by meiosis to produce
  spermatids
• primary spermatocyte (from type B cell) is
  diploid, goes through meiosis I to form 2 haploid
  secondary spermatocyte
• 2 secondary spermatocytes undergo meiosis II to
  form 4 spermatids
• spermatids undergo spermiogenesis to form viable
  (functional) sperm

Fig. 28.8, p. 1081
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Male Spermiogenesis

• Development of
• Flagellum for movement
• Acrosome (contains digestive enzymes for egg
  penetration)
• Midpiece (mitochondria -energy for movement)

Fig. 28.9, p. 1082
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Male Sustentacular Cells

• Also called Sertoli cells
• Surround and support developing spermatocytes and
  spermatids
• Extend from basal lamina to lumen of tubule

Fig. 28.8, p. 1081
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Male Sustentacular Cells

• Form blood-testis barrier
• cells joined by tight junctions - prevents
  contact between developing sperm and blood
• produce fluid different from surrounding
  interstitial fluid (higher in androgens, amino
  acids, potassium)
• important because sperm are first produced after
  immune system has developed sense of self
• sperm would be recognized as foreign if contacted
  blood

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Male Hormonal Regulation of Function

• Hypothalamus secretes GnRH
• (Gonadotropin-releasing hormone)
• ?
• Stimulates anterior pituitary to release
• FSH LH
• ? ?
• indirectly stimulates stimulates testosterone
  secretion testosterone
• stimulates spermatogenesis secretion
• stimulates inhibin secretion
• (inhibits FSH and LH production)

Fig. 28.10, p. 1085
http//www.uronet.org/visual/nov99/3.htm
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Male Testosterone

• Stimulates
• spermatogenesis
• development and maintenance of male secondary sex
  characteristics (e.g., facial hair, large
  muscles, etc.) and male reproductive organs
• development of sexual drive in CNS
• protein synthesis in muscle cells and growth of
  muscle and bone

Fig. 28.10, p. 1085
http//www.uronet.org/visual/nov99/1.htm
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Male Inhibin

• Produced by sustentacular (Sertoli) cells
• Inhibits release of gonadotropin releasing
  hormone (GnHR), which inhibits FSH and LH
  production

Fig. 28.10, p. 1085
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Female Anatomy Overview

• Consists of
• Ovaries
• Fallopian (uterine) tubes (oviducts)
• Uterus
• Vagina
• Mammary glands
• Supporting structures

http//www.med.umich.edu/lrc/coursepages/M1/anatom
y/html/radiology/pelvis/hysterosalpingogram.html
Fig. 28.11, p. 1086
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Female Ovaries

• Located lateral to uterus
• Ligaments anchor ovary to other structures
• ovarian ligament anchors ovary to uterus
• broad ligament parietal peritoneal tissue
• suspensory ligament anchors ovary to lateral
  pelvic wall
• mesovarium holds ovary between ovarian and
  suspensory ligaments
• Contains oocytes surrounded by follicles
• Release secondary oocytes into pelvic cavity

Fig. 28.14, p. 1089
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Female Uterine (Fallopian) Tubes

• Carry oocyte toward uterus
• Fimbriae (F) immediately pick up secondary oocyte
  released from ovary and transfer it into UT
• Smooth muscle and cilia of simple columnar
  epithelium help move oocyte toward uterus

Fig. 28.14, p. 1089
http//www.med.umich.edu/lrc/coursepages/M1/anatom
y/html/radiology/pelvis/hysterosalpingogram.html
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Female Uterus

• Normal site of implantation of fertilized ovum
  and development of fetus
• Layers
• endometrium (inner layer)
• myometrium (smooth muscle)
• perimetrium (covering of visceral peritoneum)

Fig. 28.14, p. 1089
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Female Uterus Endometrium

• Consists of two sublayers
• stratum functionalis (f) undergoes cyclical
  changes every month
• stratum basalis (b) overlies myometrium (m) and
  forms a new stratum functionalis
• Forms maternal part of placenta

http//www.usc.edu/hsc/dental/ghisto/rep/d_33.html
http//www.usc.edu/hsc/dental/ghisto/rep/d_34.html
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Female Myometrium Perimetrium

• Myometrium
• consists of smooth muscle
• contracts to expel sloughed off endometrial
  tissue or fetus
• Perimetrium (serosa)
• peritoneal covering

Fig. 28.14, p. 1089
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Female Cervix and Vagina

• Cervix narrow neck of uterus
• Vagina
• birth canal
• lined with stratified squamous epithelium

Fig. 28.14, p. 1089
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Mammary Glands

• Modified sweat glands
• Only functional in females
• Produce milk to nourish newborn
• Hormonal control
• prolactin - stimulates milk production in
  lactating female
• oxytocin - stimulates milk ejection

Fig. 28.17, p. 1093
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Female Ovarian Cycle Overview

• Consists of two phases Follicular (1-6 in
  diagram) Luteal (7-9 in diagram)

Fig. 28.20, p. 1097
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Follicular Phase 1st to 14th Day

• Several primordial follicles develop into primary
  follicles
• Primary follicle develops into secondary follicle
• zona pellucida (thick, transparent membrane
  around oocyte)
• begins to produce estrogens
• antrum (opening around oocyte) forms
• Secondary follicle (when antrum is present)
  becomes Vesicular follicle (Graafian follicle)
• corona radiata forms (cells surrounding oocyte)
• primary oocyte divides (finishes meiosis I) to
  form 1 secondary oocyte and 1 polar body

Fig. 28.12, p. 1087
Fig. 28.19, p. 1095
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Ovulation and Luteal Phase 14th to 28th day

• Ovulation release of secondary oocyte (arrested
  in metaphase of meiosis II) from ovary
• Luteal Phase 14th to 28th day
• cells of ruptured Graafian follicle become corpus
  luteum which begins to secrete progesterone and
  continue to secrete estrogen
• corpus luteum degenerates in about 10 days if
  pregnancy does not occur then becomes corpus
  albicans

Fig. 28.12, p. 1087
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Ovarian Cycle Hormonal Control

• Hypothalamus secretes GnRH (gonadotropin
  releasing hormone)
• GnRH stimulates release of FSH (follicle
  stimulating hormone) and LH (lutenizing hormone)
  from anterior pituitary
• FSH ( LH) stimulate follicle growth

Fig. 28.21, p. 1098
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Ovarian Cycle Hormonal Control

• Enlarged follicles begin to secrete estrogens
• Rising estrogen levels initially inhibit release
  of FSH LH from anterior pituitary, but also
  stimulate it to produce and accumulate these
  hormones (i.e., accumulate FSH and LH)

Fig. 28.21, p. 1098
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Ovarian Cycle Hormonal Control

• Once estrogen levels reach critical level, exert
  positive feedback on hypothalamus pituitary
• result is sudden surge of LH
• Surge of LH results in
• completion of meiosis I
• release of secondary oocyte from Graafian
  follicle (i.e., ovulation)
• Ovulation results from positive feedback
  influence of estrogen on secretion of LH

Fig. 28.21, p. 1098
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Ovarian Cycle Hormonal Control

• Surge of LH causes ruptured follicle to become
  corpus luteum and stimulates production of
  estrogens and progestins from it
• Increased progesterone and estrogen cause decline
  in LH corpus luteum is less stimulated and
  eventually becomes corpus albicans

Fig. 28.21, p. 1098
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Uterine (Menstrual) Cycle

• Cyclical changes in the endometrium that prepare
  it for implantation of a fertilized ovum.
• Three phases menstrual, proliferative, secretory

Fig. 28.15, p. 1091
Fig. 28.22, p. 1100
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Menstrual Phase (Days 1-5)

• Stratum functionalis is shed (passes through
  vagina as menstrual flow)
• This is a response to declining estrogen levels

http//lpc1.clpccd.cc.ca.us/lpc/zingg/anat/alectur
e/ach27f/sld021.htm
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Proliferative Phase (Days 6-14)

• Stratum functionalis rebuilt by stratum basale in
  response to stimulation from ovarian estrogens
• Endometrial glands become larger
• Estrogen induces formation of additional
  progesterone receptors
• Increased blood supply

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Secretory Phase (Days 15-28)

• Endometrium continues to develop in response to
  ovarian progesterone
• Secretion of nutrient substances begins
• Toward end, decline in progesterone results in
  declining condition of blood vessels in stratum
  functionalis, eventually resulting in its loss
  (start of next menstrual phase)

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Correlation of Hormones With Cycles

• During menstrual phase, all hormones are at their
  lowest levels
• During proliferative phase, estrogens secreted by
  ovary cause proliferation of endrometrial cells
  such that stratum functionalis is rebuilt from
  stratum basale
• During secretory phase,
• high levels of progesterone continue to stimulate
  development of stratum functionalis
• Levels of estrogen decrease somewhat

Fig. 28.22
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Disorders of Reproduction STDs

• Gonorrhea infection by Neisseria gonnorrhoeae
  bacteria causes inflammation of the urethra and
  can lead to pelvic inflammatory disease in
  females
• Syphilis infection by Treponema pallidum
  bacteria
• Chlamydia infection by Chlamydia bacteria
  causes pelvic inflammatory disease, urethritis,
  among other things
• Genital warts infection by human papillomavirus
  (HPV) causes warts in genital area increases
  probability of developing cervical or penile
  cancer
• Genital herpes infection by herpes simplex
  virus causes lesions on genital area treated
  with acyclovir

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Other Disorders of Reproduction

• Pelvic inflammatory disease (PID) - severe
  inflammation of lower peritoneal cavity generally
  caused by STDs
• Ectopic pregnancy implantation of embryo
  outside uterus (e.g., in oviduct or pelvic
  cavity)
• Hypertrophy of prostate enlargement of the
  prostate impinges on prostate urethra making
  urination difficult and increasing the likelihood
  of bladder infection common in elderly males
• Breast cancer - cancer of the mammary gland
  strikes 18 women

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Important Developmental Milestones

• 8 weeks
• ossification begins
• blood cells begin to be formed by liver
• all systems present (at least as basic plan)
• 9-12 weeks
• bone marrow begins to form blood cells
• 26 weeks
• surfactant production begins in lung
• 38-42 weeks
• birth
• if less than 38 weeks, systems not as developed
• if more than 42 weeks, placenta starts to degrade