Female Reproductive System

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Female Reproductive System

• The Highlights

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Hormones of the Female Reproductive Cycle

• Control the reproductive cycle
• Coordinate the ovarian and uterine cycles

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Hormones of the Female Reproductive Cycle

• Key hormones include
• FSH
• Stimulates follicular development
• LH
• Maintains structure and secretory function of
  corpus luteum
• Estrogens
• Have multiple functions
• Progesterones
• Stimulate endometrial growth and secretion

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Female Reproductive Organs

• Ovary female gonad
• Uterine Tubes (fallopian tube, oviduct)
• - three parts infundibulum, ampulla, isthmus

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The Female Reproductive System in Midsagital View
Figure 28.13
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The Ovaries and Their Relationships to the
Uterine Tube and Uterus
Figure 28.14a, b
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The Uterus

• Muscular organ
• Mechanical protection
• Nutritional support
• Waste removal for the developing embryo and fetus
• Supported by the broad ligament and 3 pairs of
  suspensory ligaments

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Uterine Wall Consists of 3 Layers

• Myometrium outer muscular layer
• Endometrium a thin, inner, glandular mucosa
• Perimetrium an incomplete serosa continuous
  with the peritoneum
• The site of implantation of developing embryo
• And 3 parts fundus, body, and cervix

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Female Accessory Sex Organs Uterus

• Uterine endometrium has two layers
• - basal layer
• - functional layer built up and shed each cycle

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The Uterus
Figure 28.18c
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The Uterine Wall
Figure 28.19b
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The Uterine CycleTo be discussed below
Figure 28.20
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Functions of the Ovary

• Production of a mature oocyte, capable of
  fertilization and embryonic development.
• Production of ovarian steroids (estradiol,
  progesterone).
• Production of gonadal peptides (inhibin, activin).

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Structural Organization of the Ovary

• The main functional unit of the ovary is the
  follicle.
• Follicles are composed of the oocyte, granulosa
  cells, and theca cells.

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Stages of Follicular Growth

• Follicles are present in a number of different
  stages of growth
• - primordial follicles (resting)
• - primary, secondary, and antral follicles
• - preovulatory (Graafian) follicles

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The Corpus Luteum

• After the preovulatory follicle ovulates
  (releases its egg), it forms the corpus luteum.

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FEMALE REPRODUCTIVE SYSTEM The Ovarian Cycle
? OVARY
3 to 5 million OOGONIA differentiate into PRIMARY
OOCYTES during early development
OOCYTES becomes surrounded by squamous
(follicular) cells to become PRIMORDIAL FOLLICLES
most PRIMORDIAL FOLLICLES undergo atresia leaving
400,000 at birth
oocytes at birth arrested at Meiosis I (prophase)
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FEMALE REPRODUCTIVE SYSTEM
? OVARY
THREE STAGES OF OVARIAN FOLLICLES CAN BE
IDENTIFIED FOLLOWING PUBERTY
(each follicle contains one oocyte)
(1) PRIMORDIAL FOLLICLES
- very prevalent located in the periphery of the
cortex
- a single layer of squamous follicular cells
surround the oocyte
(2) GROWING FOLLICLES
- three recognizable stages
(a) early primary follicle
(b) late primary follicle
(c) secondary (antral) follicle
(3) MATURE (GRAAFIAN) FOLLICLES
- follicle reaches maximum size
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FEMALE REPRODUCTIVE SYSTEM
? OVARIAN FOLLICLES
(1) PRIMORDIAL FOLLICLES
(2) GROWING FOLLICLES
(a) early primary follicle
- follicular cells still unilaminar but now are
cuboidal in appearance
- oocyte begins to enlarge
(b) late primary follicle
- multilaminar follicular layer cells now termed
granulosa cells
- zona pellucida appears gel-like substance rich
in GAGs
- surrounding stromal cells differentiate into
theca interna and theca externa
(b) secondary (antral) follicle
- cavities appear between granulosa cells forming
an antrum
- follicle continues to grow
- formation of cumulus oophorus and corona radiata
(3) MATURE (GRAAFIAN) FOLLICLES
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FEMALE REPRODUCTIVE SYSTEM
? HORMONAL REGULATION OF OOGENSIS AND OVULATION
HYPOTHALAMUS release of GnRF which stimulates
release of LH and FSH from the adenohypophysis
(ANTERIOR PITUITARY)
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Neuroendocrine Regulation of Ovarian Functions
Follicle Development
E2, P
Ovulation
inhibin, activin
Luteinization
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Effects of GnRH on Gonadotropins

• GnRH is released in a pulsatile manner,
  stimulating the synthesis and release of LH and
  FSH.
• GnRH acts through its receptor on the pituitary
  gonadotroph cells, stimulating production of
  phospholipase C.
• Recall that IP3 pathway causes gonadotropin
  release, while the DAG/PKC pathway causes
  gonadotropin synthesis.

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Actions of FSH on Granulosa Cells
Gene Expression
Steroidogenic enzymes LH Receptor Inhibin
Subunits Plasminogen activator
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Ovarian Estradiol Production
estradiol
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Regulation of Progesterone Production

• Progesterone is produced from theca cells, mature
  granulosa cells, and from the corpus luteum.
• In this case, gonadotropins induce expression of
• - steroidogenic acute regulatory protein
• - P450 side chain cleavage

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Actions of Estradiol

• Estradiol also has important actions in a number
  of other tissues
• - causes proliferation of uterine endometrium
• - increases contractility of uterine myometrium
• - stimulates development of mammary glands
• - stimulates follicle growth (granulosa cell
  proliferation)
• - effects on bone metabolism, hepatic
  lipoprotein production, genitourinary tract,
  mood, and cognition
• Effects are mediated through the intracellular
  estrogen receptors (alpha and beta), and possible
  membrane effects.

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Actions of Progesterone

• Progesterone exerts positive and negative
  feedback effects on gonadotropin synthesis and
  release.
• Progesterone also acts on many tissues
• - stimulates secretory activity of the uterine
  endometrium
• - inhibits contractility of the uterine
  myometrium
• - stimulates mammary growth
• The actions of progesterone are mediated through
  an intracellular P receptor, which acts as a
  transcription factor.

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FEMALE REPRODUCTIVE SYSTEM The Menstrual Cycle
? HORMONAL REGULATION OF OOGENSIS AND OVULATION
OVULATION
FOLLICULAR PHASE
LUTEAL PHASE
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FEMALE REPRODUCTIVE SYSTEM The Menstrual Cycle
? HORMONAL REGULATION OF OOGENSIS AND OVULATION
OVULATION
sharp surge in LH with simulataneous increase in
FSH
Meiosis I resumes oocyte and surrounding cumulus
break away and are extruded
oocyte passes into oviduct
ECTOPIC IMPLANTATIONS
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The Menstrual Cycle

• Women have ovulatory cycles of about 28 days in
  length.
• Day 1 of the cycle is defined as the first day of
  menstruation.
• There are two phases of the cycle, named after
  ovarian and uterine function during that phase
• - first two weeks follicular or proliferative
  stage
• - second two weeks luteal or secretory stage
• The preovulatory gonadotropin surges occur in the
  middle of the cycle (around day 14).

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The Menstrual Cycle The Ovary

• Follicular phase small antral follicles develop,
  a dominant follicle is selected and grows to the
  preovulatory stage.
• Midcycle the gonadotropin surges cause ovulation
  of the dominant follicle.
• Luteal phase the corpus luteum forms and becomes
  functional, secreting large amounts of
  progesterone, followed by estradiol (results in
  negative feedback, not positive feedback, because
  P increases before E2).
• If pregnancy does not take place, the corpus
  luteum regresses, and P and E2 levels decrease.

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The Menstrual Cycle The Uterus

• Proliferative stage increasing estradiol levels
  stimulate proliferation of the functional layer
  of the uterine endometrium.
• - Results in increased thickness of the
  endometrium.
• - Increased growth of uterine glands (secrete
  mucus) and uterine arteries.
• Secretory stage progesterone acts on the
  endometrium.
• - uterine glands become coiled and secrete more
  mucus
• - uterine arteries become coiled (spiral
  arteries)

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The Menstrual Cycle The Uterus

• If pregnancy doesnt occur, P and E2 levels
  decrease at the end of the secretory stage.
• - vasospasm of arteries causes necrosis of
  tissue
• - loss of functional layer with bleeding of
  uterine arteries (menstruation)

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FEMALE REPRODUCTIVE SYSTEM
? UTERUS
ENDOMETRIUM
undergoes cyclic changes which prepare it for
implantation of a fertilized ovum
TWO LAYERS
(1) FUNCTIONAL LAYER (stratum functionalis)
- BORDERS UTERINE LUMEN
- SLOUGHED OFF AT MENSTRATION
- CONTAINS UTERINE GLANDS
(2) BASAL LAYER (stratum basale)
- RETAINED AT MENSTRATION
- SOURCE OF CELLS FOR REGENERATION OF FUNCTIONAL
LAYER
STRAIGHT AND SPIRAL ARTERIES
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FEMALE REPRODUCTIVE SYSTEM
? HORMONAL REGULATION OF UTERINE CYCLE
(1) PROLIFERATIVE PHASE
concurrent with follicular maturation and
influenced by estrogens
(2) SECRETORY PHASE
concurrent with luteal phase and influenced by
progesterone
(3) MENSTRUAL PHASE
commences as hormone production by corpus luteum
declines
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Male Reproductive System

• The Highlights

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The Male Reproductive System in Midsagital View
Figure 28.1
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MALE REPRODUCTIVE SYSTEM
? TESTIS
TUNICA ALBUGINEA
- thick connective tissue capsule
- connective tissue septa divide testis into 250
lobules
- each lobule contains 1-4 seminiferous tubules
and interstitial connective tissue
(1) SEMINIFEROUS TUBULES
- produce sperm
INTERSTITIAL TISSUE
- contains Leydig cells which produce testosterone
(2) RECTUS TUBULES
(3) RETE TESTIS
(4) EFFERENT DUCTULES
(5) EPIDIDYMIS
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MALE REPRODUCTIVE SYSTEM
? SPERMATOGENESIS
SPERMATOGONIA
1º SPERMATOCYTE
2º SPERMATOCYTE
SPERMATIDS
SPERMATIDS
2º SPERMATOCYTE
1º SPERMATOCYTE
SERTOLI CELLS
- columnar with adjoining lateral processes
- extend from basal lamina to lumen
- Sertoli-Sertoli junctions divide seminiferous
tubules into basal and adluminal compartments
SERTOLI CELLS
SPERMATOGONIA
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Basal Lamina
Daughter cell Type A spermatogonium remain at
basal lamina as a precursor cell
2n
2n
Spermatogonia (stem cells)
2n
mitosis
Daughter cell Type B Spermatagonium
Moves to adluminal compartment
n
1 spermatocyte
Meiosis I completed
n
2 spermatocyte
n
Meiosis II
n
n
n
n
Early spermatids
n n n n
Late spermatids
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MALE REPRODUCTIVE SYSTEM
? SPERMATOGENESIS
THREE PHASES
(1) Spermatogonial Phase (Mitosis)
(2) Spermatocyte Phase (Meiosis)
(3) Spermatid Phase (Spermiogenesis)
- acrosome formation golgi granules fuse to form
acrosome that contains hydrolytic enzymes which
will enable the spermatozoa to move through the
investing layers of the oocyte
- flagellum formation centrioles and associate
axoneme (arrangement of microtubules in cilia)
- changes in size and shape of nucleus chromatin
condenses and shedding of residual body
(cytoplasm)
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MALE REPRODUCTIVE SYSTEM
? HORMONAL REGULATION OF MALE REPRODUCTIVE
FUNCTION
HYPOTHALAMUS REGULATES ACTIVITY OF ANTERIOR
PITUITARY (ADENOHYPOPHYSIS)
ADENOHYPOPHYSIS SYNTHESIZES HORMONES (LH and FSH)
THAT MODULATE ACTIVITY OF SERTOLI AND LEYDIG CELLS
Luteinizing Hormone (LH) stimulates testosterone
production by Leydig cells
Follicle Stimulating Hormone (FSH) stimulates
production of sperm in conjunction with
testosterone by regulating activity of Sertoli
cells
SERTOLI CELLS STIMULATED BY FSH AND TESTOSTERONE
RELEASE ANDROGEN BINDING PROTEIN WHICH BINDS
TESTOSTERONE THEREBY INCREASING TESTOSTERONE
CONCENTRATION WITHIN THE SEMINIFEROUS TUBULES AND
STIMULATING SPERMATOGENESIS