AP 150

1
AP 150

• Chapter 28
• The Reproductive System

2
The Uniqueness of the Reproductive System

• Different structural design of the organs of the
  reproductive systems
• Organs of other systems are exactly alike
  (except, of course, for the brains of ? and ? )
  )
• Function of the reproductive system is to
  perpetuate the species i.e., produce new viable
  offspring
• Function of other systems is to maintain
  homeostasis of the individual

3
Types of Reproduction

• Cellular used for growth and repair of bodys
  tissues
• Organismal
• Asexual - division of parent cell into 2
• New individuals are identical to cell derived
  from
• Sexual - use sex cells (gametes)
• New gene assortment in new individual
• New individuals are not identical to either
  parent
• Cause of the great diversity seen in plants,
  animals, protistans, fungi, and monera (bacteria)

4
Types of Sex

• SURPRISE! Not exactly what you thought when you
  saw the heading above, eh?!
• Phenotypic sex physical appearance of organism
• Facial hair, breasts,
• Gonadal sex determined by the type of gonads
  (sex organs) present
• Genotypic sex determined by type of sex
  chromosomes individual possesses
• XX female
• XY male

5
Reproductive System

• Primary sex organs (gonads) testes in males,
  ovaries in females
• Gonads produce sex cells called gametes and
  secrete sex hormones
• Accessory reproductive organs ducts, glands,
  and external genitalia
• Sex hormones androgens (males), and estrogens
  and progesterone (females)

6
Development of Testes

• Develop in abdominal region near site of future
  kidneys
• Descent
• Pass from abdominal cavity through inguinal canal
  to scrotum
• Guided by fibromuscular gubernaculum
• Pass through inguinal rings (bilateral oblique
  passage- ways in the anterior abdominal wall).
• Openings in aponeuroses of transverse abdominis,
  internal and external oblique.
• Weak part in abdominal wall. Herniation may occur
  here.
• Cryptorchidism
• Failure of one or both of testes to descend into
  scrotum
• Prevents normal sperm development

7
Descent of the Testes
8
Male Reproductive System

• The testes produce sperm
• Seminiferous tubules
• Pathway of spermatozoa
• Epididymis
• Ductus (Vas) deferens
• Ejaculatory duct
• Urethra
• Accessory sex glands
• Seminal vesicles
• Prostate
• Bubourethral (Cowpers) glands
• Penis

9
The Scrotum

• Sac of skin and superficial fascia that hangs
  outside the abdominopelvic cavity at the root of
  the penis
• Contains paired testicles separated by a midline
  septum
• Its external positioning keeps the testes 3?C
  lower than core body temperature (needed for
  sperm production)
• Dartos - smooth muscle that wrinkles scrotal sac
• Cremaster muscles pulls sac closer to the body
• Extensions of the internal oblique muscle of the
  abdomen

10
The Scrotum
11
The Testes

• Primary sex organs of a male
• Testis L., a witness
• Located outside the body cavity because sperm
  require lower-than-body temperature for
  development
• Testis serve as both
• Exocrine gland
• Secrete seminal fluid
• Endocrine gland
• Secrete testosterone and inhibin hormones
• Coverings of testis
• Tunica vaginalis
• Originally visceral peritoneum. Serous membrane
• Tunica albuginea - surrounds testis
• Thick white connective tissue
• Penetrates testis to divide it into lobules
  (250).
• Within lobules are seminiferous tubules and
  interstitial (Leydig) cells that secrete
  testosterone.
• Tubes in which sperm develop and move
• Seminiferous tubules. Site of sperm production
• Tubuli recti and rete testis. Pathway to
  epididymis.

12
The Testes
13
Blood Supply of the Testes

• Gonadal arteries branch off abdominal aorta at
  level of L2
• Internal pudendal arteries
• Branch off internal iliac artery
• Pampiniform plexus
• Network of veins returning blood from testis
• Empty into gonadal veins
• Gonadal veins
• Right empties into inferior vena cava
• Left empties into left renal vein

14
Gamete Formation

• Gametogenesis
• Process of forming the sex cells of the body
• Involves two processes
• Spermatogenesis - the formation of sperm
• Oogenesis - the formation of oocytes
• Every body cell has 23 pr of chromosomes (46)
• Each pair is homologous (same size and shape)
• The cell is diploid (2n chromosomal number)
• One of each pair is maternal in origin (from the
  egg)
• The other is paternal in origin (from the sperm)
• Gamete formation is by meiosis, in which the
  number of chromosomes is halved (from 2n to n)
• Gametes only have 23 chromosomes
• Contain only one of each pair
• The cell is haploid (n chromosomal number)

15
Chromosomes in Mitosis and Meiosis
Figure 28.6
16
Structure of the Seminiferous Tubule

• Composed of Sertoli cells (Nurse cells or Susten-
  tacular cells
• Extend from the basal lamina of the seminiferous
  tubule to the lumen of the tubule
• Bound together with tight junctions
• Form an unbroken layer (the blood-testis barrier)
• Prevents sperm antigens from escaping through the
  basal lamina into the blood which in turn
  prevents antibodies from attacking the developing
  (non-self) spermatocytes
• Divide testes into two compartments
• Basal compartment contains spermatogonia and
  primary spermatocytes
• Adluminal compartment contains meiotically
  active cells and the tubule lumen

17
Seminiferous Tubules

• Spermatozoa produced in seminiferous tubules.
• Each tubule ca. 31 in. long 800 total tubules
  which equal approximately gt 0.5 mile of
  tubule/testis (2600 feet)
• Formed by sustentacular (Sertoli, nurse) cells
• Nourish, protect, modify sperm cells and form a
  blood-testis barrier and produce hormones
• Interstitial cells (cells of Leydig) produce
  testosterone
• Lie outside of the seminiferous tubules (in the
  interstitium)
• Sustentacular cells convert testosterone to
  dihydrotestosterone (DHT) and estrogen.

18
The Seminiferous Tubules
19
Spermatogenesis

• Spermatogonia (stem cells) divide (mitosis) to
  form primary spermatocytes and daughter
  spermatogonia
• Primary spermatocytes divide (first division of
  meiosis) to form secondary spermatocytes
• Secondary spermatocytes divide (second division
  of meiosis) to form spermatids
• Spermatids develop an acrosome and flagellum
• Daughter spermatogonium stays behind to act as
  the new stem cell from which another primary
  spermatocyte and daughter spermatogonium will
  develop during mitosis

20
The Seminiferous Tubules
21
Spermatogenesis
22
Structure of a Spermatozoa

• Head
• Contain the genetic material (chromosomes)
• Covered by the acrosome
• Middle piece (neck)
• Location of mitochondria
• Produce energy necessary for motility of
  flagellum
• Flagellum
• Used for motility
• Only cell in human body with a one

23
Spermiogenesis Spermatids to Sperm
24
Ducts of the Male Reproductive Tract

• Efferent ductules lead out of testis
• Epididymis
• Elongated tubule with head region, body, and tail
  regions
• Lined by pseudostratified columnar epithelium
  with stereocilia
• Latter increase surface area to facilitate
  absorption of fluid from lumen of the duct
• Site of sperm cell maturation and storage
• Takes minimum of 1-2 days
• Ductus deferens or vas deferens. Passes from
  epididymis through inguinal canal into abdominal
  cavity
• Vas deferens, testicular artery and venous
  plexus, lymphatic vessels, nerves, form the
  spermatic cord
• Distal end of ductus deferens is enlarged as
  ampulla
• Wall of ductus deferens has smooth muscle that
  undergoes peristalsis as a result of sympathetic
  innervation during ejaculation
• Ejaculatory duct
• Joining of ductus deferens and duct of seminal
  vesicle in the urethra
• Ends at urethra within prostate gland

25
Male Reproductive Structures
26
Urethra

• Extends from urinary bladder to distal end of
  penis
• Passageway for urine and male reproductive fluids
• Three parts
• Prostatic urethra. Connected to bladder, passes
  through prostate.15-30 ducts from prostate empty
  into prostatic urethra.
• Membranous urethra. Extends through urogenital
  diaphragm
• Spongy or penile urethra. Passes through the
  penis. Several minute mucus-secreting urethral
  glands empty into spongy urethra

27
Accessory Glands Seminal Vesicles

• Lie on the posterior wall of the bladder and
  secrete 60 of the volume of semen
• Semen viscous alkaline fluid containing
  fructose, ascorbic acid, coagulating enzyme
  (vesiculase), and prostaglandins
• Join the vas deferens to form the ejaculatory
  duct
• Sperm and seminal fluid mix in the ejaculatory
  duct and enter the prostatic urethra during
  ejaculation

28
Accessory Glands Prostate Gland

• Doughnut-shaped gland that encircles part of the
  urethra inferior to the bladder
• Its milky, slightly acid fluid, which contains
  citrate, enzymes, and prostate-specific antigen
  (PSA), accounts for one-third of the semen volume
• Plays a role in the activation of sperm
• Enters the prostatic urethra during ejaculation

29
The Ductus Deferens and Accessory Glands
30
Accessory Glands Bulbourethral Glands (Cowpers
Glands)

• Pea-sized glands inferior to the prostate
• Produce thick, clear mucus prior to ejaculation
  that neutralizes traces of acidic urine in the
  urethra

31
Penis

• Functions urination, serves as vehicle for
  injecting sperm into vagina erection
• Three columns of erectile tissue that engorge
  with blood
• 2 Corpora cavernosa Expanded at base to form
  crus. Attached by ligaments to coxae
• 1 Corpus spongiosum surrounding spongy urethra.
  Forms the bulb
• Crura and bulb root of penis
• Glans penis enlargement of corpus spongiosum
• Prepuce or foreskin covers glans penis.
  Circumcision surgical removal
• External urethra orifice

32
Semen

• Secretions of all three accessory glands plus
  sperm cells referred to as semen.
• Urethral mucosa produces mucus
• Emission discharge of semen into prostatic
  urethra
• Ejaculation forceful expulsion of semen from
  urethra. Caused by peristalsis

33
Testosterone

• Most from interstitial cells of testes with small
  amounts from adrenal glands and sustentacular
  cells
• Causes
• enlargement and differentiation of male genitals
  and reproductive duct system
• necessary for sperm cell formation
• required for descent of testes
• hair growth on certain parts of the body
• skin is rougher and coarser
• quantity of melanin increases
• increases rate of secretion of sebaceous glands
• hypertrophy of larynx
• increases metabolic rate
• increases red blood cell count
• increases protein synthesis
• rapid bone growth
• causes closure of epiphyseal plates

34
Anatomy of Female Reproductive System

• Female reproductive organs
• Ovaries
• Uterine tubes
• Uterus
• Vagina
• External genital organs

35
Female Pelvis
36
Ligaments and Ovaries

• Broad ligament extension of peritoneum, spread
  out on both sides of uterus.
• Ligaments of ovaries
• Mesovarium peritoneal fold
• Attaches ovary to posterior surface of broad
  ligament
• Suspensory ligament from mesovarium to body
  wall. Contains ovarian arteries, veins, and
  nerves
• Ovarian ligament from ovary to superior margin
  of uterus. Ovarian arteries, veins and nerves
  enter ovary through this ligament

37
The Ovaries
Figure 27.14a
38
Ovary Histology

• Tunica albuginea capsule of dense fibrous
  connective tissue that covers ovary
• Outermost covering ovarian (germinal) epithelium
• Simple cuboidal epithelium
• Ovary
• Cortex outer, dense. Contains follicles with
  oocytes
• Medulla inner, looser. Contains blood vessels,
  nerves, lymphatic vessels
• Stroma connective tissue of the ovary

39
Maturation and Fertilization of Oocyte

• Oogenesis is the production of a secondary oocyte
  in a major follicle in ovaries
• Oogonia are cells from which oocytes develop
• Ogoonia divide by mitosis to produce other
  oogonia and primary oocytes.
• Five million oocytes produced by the 4th month of
  prenatal life.
• About 2 million begin first meiotic division but
  stop at prophase.
• All remain at this state until puberty.
• Primary oocytes are surrounded by granulosa cells
  and called a primordial follicle
• Primordial follicle becomes a primary follicle
  when oocyte and granular cells enlarge
• Primary follicle becomes secondary follicle and
  enlarges to form mature or Graafian follicle
• Usually only one oocyte is ovulated, others
  degenerate (atresia)

40
Maturation and Fertilization of Oocyte
41
Ovulation, Fertilization, Follicle Fate

• Ovulation release of a secondary oocyte from an
  ovary. Unlike spermatogenesis, division of
  cytoplasm during meiosis is uneven and polar
  bodies are very small, oocyte very large
• Graafian follicle become corpus luteum
• Fertilization begins when a sperm cell binds the
  plasma membrane of secondary oocytes and
  penetrates into cytoplasm.
• Secondary oocyte completes meiosis II forming one
  polar body. Fertilized egg now a zygote
• Fate of corpus luteum
• If fertilization occurs, corpus luteum persists
• If no fertilization, becomes corpus albicans

42
Follicle Development
43
Uterine (Fallopian) Tubes

• Transport oocyte or zygote from ovary to uterus
• Open directly into peritoneal cavity to receive
  oocyte from ovary
• Structure
• Fimbriae long thin processes that extend from
  the infundibulum. Inner surface is ciliated.
  Infundibulum is open to peritoneal cavity
• Ampulla widest part, where fertilization occurs
• Three layers outer serosa, middle muscular layer
  and inner mucosa. Mucosa simple ciliated
  columnar epithelium with longitudinal folds
• Mesosalpinx part of broad ligament directly
  associated with uterine tube
• Provides nutrients for oocyte/embryonic mass
• Cilia moves fluid and oocyte/embryonic mass
  through the tube toward uterus

44
The Uterine Tubes
45
Uterus

• Hollow, thick-walled organ located in the pelvis
  anterior to the rectum and posterosuperior to the
  bladder
• Used for
• Mechanical protection
• Nutritional support
• Waste removal for the developing embryo and fetus

46
Uterus

• Major anatomical landmarks
• Body
• Fundus
• Isthmus
• Cervix
• Cervical os (internal orifice)
• Uterine cavity
• Cervical canal
• Internal os (internal orifice)

47
The Uterus
48
Uterus

• Composed of 3 layers
• Perimetrium Outermost, serous membrane,
  continuation of the visceral peritoneum
• Myometrium Middle layer of smooth muscle
• Endometrium Thin inner, glandular mucous
  membrane lining the uterine cavity
• Contains simple tubular glands
• Functional layer innermost. Replaced monthly
  during menstrual cycle
• Basal layer deepest
• Cervix. More rigid and less contractile than rest
  of uterus
• Cervical canal. Lined with mucous glands. Glands
  secrete mucus that covers the external os and
  blocks sperm entry except during midcycle

49
Endometrium

• Has numerous uterine glands that change in length
  as the endometrial thickness changes
• Stratum functionalis
• Undergoes cyclic changes in response to ovarian
  hormones
• Is shed during menstruation
• Stratum basalis
• Forms a new functionalis after menstruation ends
• Does not respond to ovarian hormones

50
Uterine Vascular Supply

• Uterine arteries arise from the internal iliacs
• Ascend the sides of the uterus and send branches
  into the uterine wall
• Arcuate arteries branches of the uterine
  arteries
• Give rise to radial branches
• Radial branches penetrate endometrium and give
  off
• Straight arteries to the stratum basalis
• Spiral arteries to the stratum functionalis

51
Peritoneal Pouches

• Several cul-de-sacs of peritoneum exist around
  the uterus
• Vesicouterine pouch lies between the bladder
  and the uterus
• Rectouterine pouch lies between the rectum and
  the uterus

52
Supports of the Uterus

• Mesometrium portion of the broad ligament that
  supports the uterus laterally
• Uterosacral ligaments paired ligaments that
  secure the uterus to the sacrum
• Round ligaments bind the anterior wall to the
  labia majora

53
Vagina

• Major functions
• Female organ of copulation
• Provides a passageway for birth
• Passageway for elimination of menstrual flow
• Lies between the bladder and the rectum,
  extending from the cervix to the exterior of the
  body
• Muscular walls with mucous membrane lining (moist
  stratified squamous epithelium).
• Longitudinal columns and transverse rugae
• Fornix superior domed portion attached to sides
  of cervix

54
External Genitalia Vulva (Pudendum)

• All structures that lie external to the vagina
• Components include the
• Mons pubis - round, fatty area overlying the
  pubic symphysis
• Vestibule - space between labia minora into which
  urethra and vagina open
• Labia majora elongated, hair-covered, fatty
  skin folds homologous to the male scrotum
• Labia minora - hair-free skin folds lying within
  the labia majora homologous to the ventral penis

55
External Genitalia Vulva (Pudendum)

• Clitoris - button-like structure located near
  anterior junction of the labia minora
• Homologous to male penis
• Vestibular bulb - aggregates of erectile tissue
• An integral part of the clitoris
• Found throughout vestibule
• Greater vestibular glands Bartholins glands)
• Pea-size glands flanking the vagina
• Homologous to the bulbourethral glands
• Secrete mucus the vestibule moist and lubricated

56
External Genitalia Vulva (Pudendum)

• Perineum
• Diamond-shaped region between the pubic arch and
  coccyx
• Bordered by the ischial tuberosities laterally

57
Oogenesis

• Production of female sex cells by meiosis
• In the fetal period, oogonia (2n ovarian stem
  cells) multiply by mitosis and store nutrients
• Primordial follicles appear as oogonia are
  transformed into primary oocytes
• Primary oocytes begin meiosis but stall in
  prophase I

58
Oogenesis Puberty

• At puberty, one activated primary oocyte produces
  two haploid cells
• The first polar body
• The secondary oocyte
• The secondary oocyte arrests in metaphase II and
  is ovulated
• If penetrated by sperm the second oocyte
  completes meiosis II, yielding
• One large ovum (the functional gamete)
• A tiny second polar body

59
Events of Oogenesis
60
Mammary Glands

• Organs of milk production located within mammae
  or breasts
• Modified sweat glands
• Structure
• Alveoli lined by milk-secreting cells
• Cells surrounded by myoepithelial cells
• Alveoli form lobules
• Each lobule has a lactiferous duct
• Lactiferous ducts drain into the nipple
• Coopers ligaments support the breasts