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Chapter 22
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Introduction
• Male and female reproductive systems are connected sets of organs and
glands.
• Secrete hormones to regulate reproductive processes
• Develop & maintain secondary sex characteristics.
• Reproductive organs produce and nurture sex cells and transport them to
sites of fertilization.
Meiosis and Sex Cell Production
• Testes (male gonads): Produce sex cells are called sperm.
• Ovaries (female gonads): Produce sex cells are called ova (oocytes, eggs).
• Sex cells have 1 set of genetic instructions found on 23 chromosomes,
• Other body cells have 46 chromosomes
• When the sperm and egg unite at fertilization, the genetic information carried
on 46 chromosomes is restored.
• Sex cells are produced by a special type of division called meiosis.
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Figure 22.1 Homologous Chromosomes
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3
Meiosis and Sex Cell Production2
• Body Cells are diploid: containing 46 chromosomes arranged in 23
homologous pairs (includes the cells that form the gametes
• Homologous chromosomes contain the same gene for
the same characteristics (ex: hair color)
• The genes may not be identical, because a gene may
have variants (ex: Brown hair; red hair)
• Prior to meiosis, each chromosome replicates
• The original chromosome and the copy are called
chromatids and are connected by a centromere.
Meiosis includes 2 successive divisions, called the first (meiosis I) and second
(meiosis II) meiotic divisions.
1) Meiosis I separates homologous (the same, gene for gene) pairs of
chromosomes:
•
Results in haploid cells, which contain 1 set of chromosomes; these chromosomes
are still replicated, containing 2 chromatids.
2) Meiosis II separates the chromatids, producing cells that are still haploid, but
whose chromosomes now have 1 chromatid.
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First Meiotic Division
There are 4 phases in Meiosis I:
Prophase I:
• Involves synapsis: pairing of
homologous chromosomes.
• Each daughter cell receives only 1
replicated member of each
chromosome pair; this reduces the
chromosome number by half.
Telophase I:
• Crossover occurs: exchange of genetic Cell divides completely, forming 2 new
material between homologous
daughter cells.
chromosomes, to produce
chromosomes with genetic information
from both parents.
Metaphase I:
• Chromosome pairs line up on midline of
spindle.
• Alignment is random, with respect to
maternal or paternal origin.
Anaphase I:
• Homologous chromosome pairs
separate, each replicated member
migrating to a different pole.
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Figure 22.2 First Meiotic Division
After pairing, or synapsis, of homologous chromosomes occurs, chromatids
engage in crossing over, in which recombination occurs. This results in new
genetic combinations, and ensures that each new organism is unique.
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Second Meiotic Division
Meiosis II begins after Telophase I.
This division is similar to mitosis.
There are 4 phases in Meiosis II:
Prophase II:
•
This division ends with each sex cell
having 1 set of genetic instructions, or
23 chromosomes, compared to 2 sets
(46 chromosomes) in other cells.
Chromosomes condense and reappear,
still replicated.
Metaphase II:
•
Replicated chromosomes attach to
spindle fibers, along midline.
Anaphase II:
•
Centromeres separate, and chromatids
migrate to opposite poles.
Telophase II:
•
Each of 2 cells produced in Meiosis I
divides into 2 daughter cells.
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Crossing Over in Meiosis
Crossing over during meiosis results in recombination of genetic
material, which provides for unique combinations of traits in offspring.
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Organs of the Male Reproductive System
Functions of the male reproductive organs:
• To develop and maintain male sex cells (sperm).
• To transport sperm and fluids to outside of body.
• To synthesize male sex hormones.
Primary sex organs, or gonads, are the 2 testes, in which sperm cells, or
spermatozoa, and the male sex hormones are produced.
The other structures are the accessory sex organs, both internal and external.
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Descent of the Testes
In a male fetus, the testes originate
from masses of tissue behind the
parietal peritoneum, near the
kidneys.
Usually 1 – 2 months before birth,
testosterone produced by the
developing testes triggers their
descent into the Scrotum.
•
The gubernaculum aids the descent
through the inguinal canal.
After descent, spermatic cord
contains the ductus deferens, blood
vessels, and nerves.
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Structure of the Testes
Tunica albuginea:
Interstitial cells (cells of Leydig):
• Tough, fibrous capsule enclosing
• Lie between seminiferous tubules.
each testis.
• Produce and secrete male sex
Lobules:
hormones.
• About 250 compartments in testis, Rete testis:
separated by connective tissue
• Channels that transport sperm from
septa.
testis to epididymis
Seminiferous tubules:
Epididymis:
• Highly coiled tubules inside lobules.
• Coiled tube on surface of testis, that
• Lined with a special stratified
transports sperm from rete testis to
epithelium containing spermatogenic
ductus deferens
cells that give rise to sperm cells.
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Figures 22.7 and 22.8 Structure of the Testes
Right: © McGraw-Hill Education/Al Telser
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12
Male Internal Accessory Organs
The male internal accessory
organs nurture and transport
sperm cells:
• Epididymides.
• Ductus deferentia.
• Ejaculatory ducts.
• Urethra.
• Seminal vesicles.
• Prostate gland.
• Bulbourethral glands.
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Epididymides
Epididymides:
Singular is epididymis
•
•
•
•
•
Narrow, tightly coiled tubes at top of
each testis.
Connected to ducts in the testis.
Run between testis and ductus (vas)
deferens.
Promote maturation of sperm cells.
Lined with pseudostratified columnar
epithelium with nonmotile cilia.
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Ductus (Vasa) Deferentia
Ductus deferentia:
Singular is ductus (vas) Deferens
• Muscular tubes, 45 cm long.
• Part of the spermatic cord.
• Each extends from the
epididymis to the ejaculatory
duct.
• Lined with pseudostratified
columnar epithelium.
both:
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Seminal Vesicles
Seminal Vesicles:
Also called seminal glands
• Each is attached to a ductus
deferens near base of the
urinary bladder.
• Secrete alkaline fluid, which
regulates pH in male and female
tracts.
• Secrete fructose and
prostaglandins.
• Contents empty into the
ejaculatory duct.
• Contributes most of volume of
semen.
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Prostate Gland
Prostate Gland:
• Surrounds the proximal portion of
•
•
•
•
•
•
•
the urethra.
Lies just inferior to urinary bladder.
The ducts of the gland open into
the urethra.
Composed of tubular glands in
connective tissue.
Also contains smooth muscle.
Secretes a thin, milky, alkaline
fluid.
•
Prostate specific antigen
•
Fructose
Secretion enhances sperm motility.
Contributes to volume of semen.
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Milkrofotografle/Medical Images
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Hill LLC.
Clinical Application 22.1
Prostate Cancer
• Many cases are slow-growing, and do not require treatment, but some
cases are serious or even fatal.
• Diagnosed with help of a rectal exam, to check for enlarged prostate.
• Some men experience frequent and slowed urination.
• Blood test for elevated prostate-specific antigen (PSA) is used in diagnosis.
• PSA may be elevated above normal due to inflammation (prostatitis) or
enlargement (benign prostatic hyperplasia).
• A man with prostate cancer can also have a normal level of PSA.
• When cancer cells are present, excess PSA is produced.
• Biopsy is done for a man with an enlarged prostate and elevated PSA.
• Treatments include surgical removal of prostate gland, radiation, and
hormones.
• New tests measure expression of specific genes that change activity
significantly when the disease spreads.
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Bulbourethral Glands
Bulbourethral Glands:
•
•
•
•
Also called Cowper’s glands.
Inferior to the prostate gland.
Secrete mucus-like fluid.
Fluid released in response to
sexual stimulation.
• Lubricates end of penis.
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Semen
Semen:
•
•
The fluid transported by urethra to the outside of the body during ejaculation
Contains sperm + various secretions of the accessory reproductive glands
Semen composition and properties:
• Contains sperm cells from the testes.
• Contains secretions of the seminal vesicles, prostate gland, and bulbourethral
glands.
• Slightly alkaline, pH = 7.5.
• Contains prostaglandins.
• Contains nutrients.
• Volume is 2 - 5 mL of semen per ejaculation.
• Averages 120 million sperm cells per mL of semen.
• Sperm begin to swim as they mix with secretions of accessory glands.
•
Sperm cannot fertilize egg until they go through capacitation in female tract, which
weakens acrosome (cap over sperm head)
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Clinical Application 22.2
Male Infertility:
•
Inability of sperm cells to fertilize an oocyte.
Causes of male infertility:
• Failure of testes to descend into scrotum during fetal
development.
• Inflammation of testes from certain diseases, such as mumps.
• Poor-quality sperm: abnormal head, acrosome or tail.
• Low sperm count, less than 20 million/mL of ejaculate.
Computer-aided sperm analysis (CASA):
• Technique used to evaluate a man’s fertility.
• Analyzes sperm count, sperm motility, size and shape of sperm
parts
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Male External Reproductive Organs
Male external reproductive organs:
Scrotum, and the penis:
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Scrotum
Scrotum:
• Pouch of skin and subcutaneous tissue, located behind penis.
• Subcutaneous tissue lacks fat.
Dartos muscle:
Smooth muscle in subcutaneous tissue
• Contracts and relaxes in response to temperature changes
• Keeps the testes at optimal temperature for sperm production and survival (~ 5o F
below body temperature)
• Medial septum divides the scrotum into 2 chambers:
•
Each chamber is lined with a serous membrane.
•
Each chamber houses a testis and epididymis.
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Penis
Penis:
•
Conveys urine and semen through urethra to outside of body.
•
Specialized to become erect for insertion into the vagina during sexual intercourse.
Body (shaft) contains 3 columns of erectile tissue:
• 2 corpora cavernosa.
• 1 corpus spongiosum, which surrounds urethra.
Glans penis is distal enlargement of corpus spongiosum.
Prepuce (foreskin) is covering of glans penis; removed during circumcision.
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Erection, Orgasm, and Ejaculation
Erection:
•
During sexual stimulation, parasympathetic nerve impulses release nitric
oxide, which dilates arteries of penis
•
Pressure of arterial blood compresses veins
•
Blood accumulates in the erectile tissues
•
Penis swells and elongates
Orgasm:
•
Culmination of sexual stimulation
•
Pleasurable feeling of physiological and psychological release
•
Accompanied by emission and ejaculation:
•
Emission is the movement of semen into the urethra
•
Ejaculation is the movement of semen out of the urethra
•
Dependent on sympathetic nerve impulses
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25
Erection, Orgasm, and Ejaculation
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Formation of Sperm Cells
Sustentacular (Sertoli) Cells:
•
•
Spermiogenesis:
Large cells, spanning the entire thickness of •
the epithelium of a seminiferous tubule
Support and nourish spermatogenic cells
throughout their development into sperm
Sperm formation sequence:
•
Spermatogonia → primary spermatocytes →
secondary spermatocytes → spermatids →
spermatozoa.
•
Meiosis reduces the number of
chromosomes in each cell by half.
The development of spermatids into sperm.
Spermatogenesis:
•
Combined processes of meiosis and
spermiogenesis.
Spermatocytes arise from
spermatogonia. During
spermatogenesis, 4 sperm cells are
produced from meiosis of 1 primary
spermatocyte.
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Formation of Sperm Cells
During spermatogenesis:
• Spermatogonia replenish
themselves
• also give rise to spermatocytes,
which develop into sperm.
As the stages of spermatogenesis
continue
• the developing sperm migrate
from the outer edge of the
seminiferous tubule to the lumen.
Sustentacular cells support the
entire process.
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Structure of a Sperm Cell
Sperm cell is a tiny tadpole-shaped
structure.
Parts of a sperm cell:
Head:
• Nucleus contains 23 chromosomes.
• Acrosome: cap over the nucleus, which
contains enzymes that aid in
penetrating layers around oocyte
during fertilization.
Tail (flagellum):
• Contains many microtubules enclosed
in extension of cell membrane; lashing
movement propels the sperm toward
the egg.
Midpiece:
• Contains many mitochondria, which
provide ATP for swimming.
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Hormonal Control of Male Reproductive
Function
Male reproductive functions:
•
Controlled by hormones secreted by the hypothalamus, the anterior pituitary
gland, and the testes.
Hormones:
•
Initiate and maintain sperm cell production
•
Oversee the development and maintenance of male secondary sex
characteristics, which are special features associated with the adult male
body.
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Male Sex Hormones
Androgens.
• Male sex hormones
• Interstitial cells in the testes produce most of them, but small amounts are made in
the adrenal cortex.
• Testosterone is the most important androgen.
•
•
Secretion begins during fetal development and continues until several weeks after birth,
after which secretion nearly stops during childhood.
Secretion begins again during puberty and continues throughout life.
• Dihydrotestosterone (DHT):
•
Androgen derivative of testosterone
•
Acts on cells in prostate gland, seminal vesicles, external accessory organs
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Actions of Testosterone
Prior to birth:
• Development of male reproductive organs.
• Descent of testes into scrotum.
During puberty:
• Enlargement of testes (primary sex characteristic) and accessory organs of male
reproductive system.
• Development of secondary sex characteristics, which continue after puberty:
•
Increased growth of body hair.
•
Sometimes decreased growth of scalp hair.
•
Enlargement of the larynx and thickening of the vocal cords.
•
Thickening of the skin.
•
Increased muscular growth.
•
Thickening and strengthening of the bones.
Testosterone also increases rate of red blood cell production and cellular
metabolism.
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Organs of the Female Reproductive System
Specialized functions of the female
reproductive organs:
Primary female sex organs (gonads)
are ovaries.
• Produce female sex cells (egg cells, or
oocytes).
• Transport oocytes to site of
fertilization.
• Provide favorable environment for
developing offspring.
• Transport offspring to outside the
body.
• Produce female sex hormones.
•
Accessory (secondary) female sex
organs are the internal and external
reproductive organs.
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Ovaries and Ovarian Attachments
The ovaries are solid, oval structures
which lie in the lateral wall of the
pelvic cavity.
Several ligaments hold each ovary in
position:
• Broad ligament:
•
Largest ligament; holds ovary in place
and is also attached to the uterine
tubes and uterus.
• Suspensory ligament:
•
Holds the ovary at the upper end.
• Ovarian ligament:
•
Attaches lower end of ovary to uterus.
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Ovaries
Ovary Descent
•
The ovaries develop from masses of tissue posterior to the parietal peritoneum,
near the developing kidney.
•
The ovaries descend to locations just inferior to the pelvic brim, where they
remain attached to the lateral pelvic wall.
Ovary Structure
• The ovarian medulla
•
Mostly loose connective tissue
•
Contains many blood vessels,
lymphatic vessels, and nerve
fibers.
• The ovarian cortex
•
Contains tiny masses of cells called
ovarian follicles
•
Egg cells develop inside these
follicles.
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Female Internal Accessory Reproductive Organs
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Uterine Tubes
Uterine tubes:
• Also called fallopian tubes or oviducts.
• Tubular organ that transports ovulated egg cell from ovary to uterus.
• End near ovary is funnel-like infundibulum with extensions called fimbriae.
•
Fimbriae lie in close proximity to ovary, so they pick up ovulated egg cell.
• Mucosa is lined with cilia, which aid in transport of egg down uterine tube.
• Peristaltic contractions help move secondary oocyte down the uterine tube
• Fertilization occurs in uterine tube
a: without
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the priorEducation/Al
written consent
of McGraw
Hill Gschmeissner/Science
LLC.
Uterus
Uterus:
• Hollow, muscular, pear shaped organ.
• Receives the embryo and sustains its
development.
• Attached to pelvic walls by broad ligament and
round ligament.
Regions of uterus:
• Body: upper 2/3 ; has dome shaped top
(fundus).
• Cervix (or neck): lower 1/3; partially extends
into upper vagina.
Layers of uterine wall:
•
Endometrium (mucosa).
•
Myometrium (muscle layer).
•
Perimetrium (serosa).
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Vagina
Fibromuscular tube that runs
Wall of vagina has 3 layers:
between the uterus and the outside 1) Inner mucosal layer of stratified
squamous epithelium.
of body.
•
Conveys uterine secretions
•
Receives the penis during
intercourse
•
Provides a passageway for
offspring during birth.
•
Surrounds end of cervix.
2)
3)
Middle muscular layer.
Outer fibrous layer.
Fornices: recesses between upper
vaginal wall and cervix.
Vaginal orifice:
• Partially enclosed by hymen, a thin
layer of connective tissue and
stratified squamous epithelium.
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Female External Reproductive Organs
The female external reproductive organs surround the openings of the
urethra and vagina, and are known as the vulva;
Vestibule:
Labia majora:
• Space between the labia minora that
• Rounded folds of adipose tissue and
encloses the vaginal and the urethral
skin
openings.
• Enclose and protect the other external
reproductive organs.
• The vestibular (Bartholin’s) glands
secrete mucus into the vestibule during
• Merge to form a rounded elevation
sexual stimulation.
over the symphysis pubis, the mons
pubis.
Labia minora:
• Flattened, longitudinal folds between
the labia majora.
• Well supplied with blood vessels.
• At anterior end, they form a hood-like
covering around clitoris.
Clitoris:
• Small projection between labia
minora, at anterior end of vulva.
• Corresponds to the male penis;
composed of 2 columns of erectile
tissue.
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Erection, Lubrication, and Orgasm
Erection:
Orgasm:
•
•
Clitoris responds to sexual stimulation.
•
Sexual stimulation ends with orgasm,
pleasurable feeling of physiological and
psychological release.
•
Erectile tissues in clitoris and around
vaginal entrance respond to sexual
stimulation.
Nitric oxide dilates arteries in erectile
tissue, expanding vagina.
•
Lubrication:
•
Sexual stimulation causes vestibular
glands to secrete mucus into vestibule.
•
Mucus lubricates vestibule and vagina,
to aid in intercourse.
Muscles of perineum, uterus, and
uterine tubes contract rhythmically,
which helps transport sperm toward
uterine tubes.
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Primordial Follicles
During prenatal development of a female primordial germ cells called oogonia
divide by mitosis to produce more oogonia in the fetal ovaries.
•
The oogonia develop into primary oocytes.
Each primary oocyte is closely surrounded by a layer of flattened epithelial
cells called follicular cells, forming a primordial follicle.
•
•
Early in fetal development, primary oocytes begin the process of meiosis
The process soon stops, and does not start again until puberty.
Once the primordial follicles are produced during fetal development, no new
ones are produced.
The number of oocytes continually declines
•
90% of the primordial follicles present at birth are lost to apoptosis (programmed
cell death) between birth and early adulthood.
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Oogenesis
Oogenesis is the process of egg cell
formation.
a) Beginning at puberty, some primary
oocytes continue meiosis (Meiosis I),
creating diploid cells.
b) Primary oocyte divides
•
•
Forms a large secondary oocyte and a
small first polar body;
Secondary oocyte is a future ovum
(egg cell), which may be fertilized by a
sperm in the future.
c) Secondary oocyte starts Meiosis II,
then stops at Prophase II
•
•
When fertilized, oocyte finishes
Meosis II resulting in a tiny second
polar body and a zygote (fertilized
egg).
Polar bodies allow for the formation
of an egg cell with large amounts of
cytoplasm and organelles, and a
haploid number of chromosomes.
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Follicle Maturation
1
At puberty
•
Anterior pituitary gland secretes increased amounts of FSH, and the ovaries enlarge
in response.
With each reproductive cycle, some of the primordial follicles mature into
primary follicles:
• Primary oocyte enlarges.
• Follicular cells proliferate into
several layers of granulosa cells.
• Zona pellucida, a glycoprotein
layer, forms between oocyte
and granulosa cells.
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Follicle Maturation
2
While a follicle is developing, ovarian (follicular) cells outside follicle
organize into layers:
•
Inner vascular layer (theca interna) produces steroids (estrogens &
progesterone.
•
Outer vascular layer (theca externa) consists of connective tissue.
a)
Follicular cells proliferate into 6 – b) 15 more days of development
12 layers.
convert an antral follicle into a
mature antral (preovulatory, or
May take 150 days for primordial
Graafian) follicle.
follicle to become pre-antral follicle.
•
•
Fluid-filled spaces form among the
cells.
•
•
a)
Spaces merge into a large cavity called
the antrum,
Oocyte becomes pressed to 1 side of
follicle.
65 – 70 days of development
convert the pre-antral follicle into
an antral follicle.
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Follicle Maturation
3
Several primary follicles may begin maturing at any one time
• Usually only the dominant follicle fully develops, and the others degenerate.
• It takes about 300 days for a primordial follicle to develop into a mature
antral follicle.
Continuous process of follicle development in the ovaries
•
a new mature antral follicle ready for ovulation with each menstrual cycle.
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Ovulation
Close to end of follicle maturation,
•
Primary oocyte undergoes meiosis I,
•
Producing a secondary oocyte and first polar body
Process of ovulation releases the secondary oocyte and first polar body
from mature antral follicle
Ovulation triggered by surge of LH released from anterior pituitary
gland
•
Wall of follicle swells, weakens, and ruptures
•
Secondary oocyte and 1 or 2 layers of surrounding follicular cells are usually
propelled to the opening of the nearby uterine tube by fimbriae
Oocyte must be fertilized within hours, or it degenerates
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47
Figure 22.31 Follicle During Ovulation
© P.M. Motta and J. Van Blerkom/Science Source
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48
Female Sex Hormones
Androgens:
•
•
Secreted by adrenal cortex
Cause growth of pubic and axillary hair at puberty
Estrogens and Progesterone:
•
•
Secreted by ovaries, adrenal cortices, and the placenta during pregnancy:
Estrogens:
• Progesterone:
•
Stimulate enlargement of accessory
reproductive organs.
•
Stimulates uterine changes during
menstrual cycle.
•
Stimulate thickening of the
endometrium.
•
Affects mammary glands.
•
Regulates secretion of gonadotropins.
•
Develop and maintain female
secondary sex characteristics:
•
Breast and mammary gland duct
development.
•
Increased adipose tissue in
breasts, thighs, buttocks.
•
Increased vascularization of skin.
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Menstrual Cycle
Regular, monthly changes in the ovary and uterus which culminates in
menstrual bleeding (menses).
•
•
Begins around age 13 and continues into early 50s.
Menarche: 1st reproductive cycle.
Ovarian cycle
• Hypothalamus secretes Gonadotropin Releasing Hormone (GnRH) that
stimulates the anterior pituitary gland
• Anterior pituitary gland secretes FSH & LH that regulate the ovary
Uterine Cycle
• Development of the endometrium is regulated by estrogen & progesterone
secreted by the ovarian follicles
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Ovarian Cycle
1. Follicular phase:
2.
If no fertilization
• FSH & LH stimulate ovarian
follicle maturation
• Corpus luteum degrades  corpus
albicans
• Follicles secretes estrogen
• ↓ estrogen & progesterone no longer
inhibits FSH & LH secretion
Ovulation
• Occurs on Day 14
If fertilization occurs
• Surge in LH secretion stimulates •
ovulation
3. Luteal Phase
• Remaining follicle degrades 
corpus luteum
•
Corpus luteum continues to secrete
estrogen & progesterone until the
placenta forms.
Estrogen & progesterone maintains
the endometrium
• Corpus luteum secretes
estrogen & progesterone
•
Prepares endometrium for
developing embryo
•
Inhibits FSH & LH secretion
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Uterine cycle
1) Proliferation phase
•
Estrogen causes endometrium
to thicken
•
Occurs during the Follicular
phase
2) Secretory phase
•
Occurs during the Luteal phase
•
Estrogens continue to stimulate
endometrium development
•
Progesterone causes the
endometrium to become more
vascular & glandular
Endometriosis
• Endometrial tissue grows
outside of the uterus
(endometrial implant).
•
Most commonly in the ovaries,
bowel or the tissue lining the
pelvis.
• Displaced endometrial tissue
thickens & breaks down with
each menstrual cycle
3) Menses
•
Corpus luteum  Corpus
albicans
•
↓ estrogen & progesterone
causes endometrium to
disintegrate & slough off
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Menstrual Cycle
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Clinical Application 22.3
Female Infertility
• Infertility: inability to conceive a child after 1 year of trying.
•
•
Males and females contribute equally to infertility.
25% of cases due to more than one factor, according to the American Society for
Reproductive Medicine.
Causes of female infertility:
• Anovulation: Hyposecretion of FSH and LH from anterior pituitary, and resulting lack of
ovulation.
• Endometriosis: Endometrial tissue grows in abdominal cavity; fibrosis occurs, which
may encase ovary or obstruct uterine tubes.
• Infections, such as gonorrhea
•
Can obstruct uterine tube, or cause production of a viscous mucus that prevents sperm from
entering uterine tube.
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Menopause
Menopause (female climacteric):
• The stopping of the menstrual cycles.
• Usually occurs in the late 40s or the early 50s.
• The ovaries no longer produce as much estrogens and progesterone as
they did previously.
• Some female secondary sex characteristics may disappear.
• 50% of women experience hot flashes.
• Migraine headaches, backaches and fatigue occur in some women.
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Mammary Glands
Mammary glands:
• Specialized to secrete milk following
pregnancy, to nourish baby.
• The nipple of each breast is
surrounded by a circular area of
pigmented skin call the areola.
• The mammary glands of males and
females are similar.
•
As puberty is reached, ovarian
hormones stimulate development of
the mammary glands in females.
A mammary gland is composed of 15 - 20 irregularly shaped lobes.
• Each lobe contains alveolar glands, drained by alveolar ducts, which drain into a
lactiferous duct that leads to the nipple and opens to the outside.
• Dense strands of connective tissue form suspensory ligaments that support the
breast.
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Birth Control
Voluntary regulation of the number of & time offspring are conceived.
• Requires some type of contraception,
• a method which can avoid fertilization or prevent implantation.
Coitus interruptus:
Chemical barriers:
•
Withdrawing the penis prior to ejaculation •
•
Not very effective, since sperm can leave
urethra before ejaculation.
•
Spermicides in form of creams, foams, and
jellies
Most effective when used with a
mechanical barrier.
Rhythm method:
•
•
Requires abstinence from sexual
intercourse 2 days before and 1 day after
ovulation;
Not very effective, since it is difficult to
predict the exact time of ovulation.
Mechanical barriers:
•
•
Prevent sperm from entering female tract
during sexual intercourse;
Ex: male and female condoms; diaphragm
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Birth Control Methods
2
Combined Hormone Contraceptives:
• Deliver estrogen and progesterone to prevent pregnancy.
•
Contain synthetic chemicals that function like estrogen and progesterone.
• Disrupt normal FSH and LH secretion, which prevents follicle maturation and
ovulation.
•
Also thicken cervical mucus to prevent sperm passage.
•
Various methods are used to deliver hormones.
Other Hormone Contraceptives:
• An intramuscular injection of
medroxyprogesterone acetate
•
Prevents maturation & release of a
secondary oocyte.
• Protects for 3 months,
Intrauterine Device (IUD):
• Copper T (non hormonal)
• Hormonal IUD
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Birth Control Methods 3
Emergency Contraception:
• Morning-after pill can be taken 3 to 5 days after intercourse
• Works by temporarily stopping ovulation
• Prevents pregnancy, but does not work if ovulation have already
occurred
Sterilization:
• Surgical procedures that
permanently prevent pregnancy
Vasectomy (male):
• Removal of a small section of ductus
deferens, and cut ends are tied
• Prevents sperm from leaving
epididymis
Tubal ligation (female):
• Uterine tubes are cut, and ends are tied
• Prevents sperm from reaching oocyte
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59
Figure 22.36 Sterilization Methods
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60
Sexually Transmitted Infections (STIs)
Termed STIs instead of STDs (sexually transmitted diseases), because a
person can be infected and contagious, without developing symptoms of the
disease
Symptoms of STIs:
Pelvic inflammatory disease:
•
Burning sensation during urination
•
•
Pain in the lower abdomen
Complication associated with gonorrhea or
chlamydia
•
Fever or swollen glands in the
neck
•
Bacteria enter vagina and spread to
reproductive organs
•
Discharge from the vagina or the
penis
•
Can scar uterine tubes, resulting in infertility
•
Pain, itch, or inflammation in the
genital or the anal area
•
Sores, blisters, bumps, or rashes
•
Itchy, runny eyes
Acquired immune deficiency syndrome
(AIDS):
•
HIV can be transmitted through semen (in
unprotected sex), blood, milk
•
Causes deterioration of body’s immune
defenses
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