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Human reproduction
Male Reproductive System
Organs:
2 Testes – produce sperm and sex hormones.
Hormones influence sperm production and
secondary sex traits.
2 Epididymides – sperm maturation, storage
2 Vas Deferentia – rapid transport of sperm
2 Ejaculatory Ducts – conduct sperm to penis
1 Penis – sexual intercourse organ
Male Reproductive System (continued)
Accessory Glands:
2 Seminal Vesicles – secrete fructose (sperm use this
sugar for energy) and prostaglandins (induce
muscles to contract)
1 Prostate Gland – secretes most of the liquid part of
semen (sperm + glandular secretions). May help
buffer the low pH (3.5-4.0) of vaginal fluid.
2 Bulbourethral (Cowper’s) Glands – a mucus-rich
lubricant
SCROTUM
Outpouching of skin
that contains both
testes; can be moved
closer to or farther
from body to help
maintain temperature
suitable for sperm
formation.
Figure 39.12(a) from page 656 of your text
PROSTATE GLAND EJECULATORY DUCT
URETHRA
SEMINAL VESICLE
BULBOURETHRAL GLAND
VAS DEFERENS EPIDIDYMIS
PENIS
TESTIS
urethra
erectile tissue
urinary bladder
anus
Figure 38. from page 657 of your text
vas deferens
epididymis
testis penis
seminal vesicle
prostate gland bulbourethral gland urethra seminiferous tubule
Figure 38. from page 658 of your text
Sertoli cell
spermatogonium (diploid) primary spermatocyte
MITOSIS MEIOSIS I MEIOSIS II part of the lumen of a seminiferous tubule
immature sperm (haploid)
late spermatid
secondary spermatocyte
early spermatids head (DNA in enzyme-rich cap)
midpiece with mitochondria
tail (with core of microtubules)
Figure 39. from page 659 of your text
Sperm
• Head is packed with DNA; cap has enzymes to
penetrate membrane surrounding egg.
• Mitochondria behind head provides energy for
flagellum.
• Produced continuously from puberty to death.
• Millions are in different stages of development
at any time.
• Takes 9-10 weeks for each sperm to form.
• Meiosis occurs inside the spermatogonia in
seminiferous tubules inside the testes.
Hormonal control of
sperm production
Hypothalamus and Anterior Pituitary
Fig. 38.17, p. 659
PITUITARY
Prostate Cancer
1. Second leading cause of death in
American men.
2. Detection
• Digital rectal exam by physician
• Blood tests for prostate-specific
antigen (PSA), a tumor marker
Menstrual Cycle
hormonal control
Hypothalamus regulates thirst, hunger, sleep, libido and endocrine functions.
hypothalamus
anterior lobe of pituitary hypothalamus gland
FSH-RF
FSH+LH
Hypothalamus releases Follicle stimulating hormone releasing factor (FSH-RF), which induces the pituitary to secrete Follicle stimulating hormone (FSH) and a little Leutenizing hormone (LH).
Menstrual Cycle
hormonal control
1. FSH and LH stimulate a follicle to begin maturing.
uterus^ vagina
oviduct
ovaries
oviduct
Ovarian cycle
secondary oocyte
antrum
primordial follicle
first polar body
- Follicle grows and matures.
- Follicle begins releasing estrogen.
- Estrogen trigger a thickening of the uterine lining.
- As estrogen levels increase hypothalamus releases LH-RF), which stimulates pituitary to secrete Leutenizing hormone.
- LH tell mature follicle to burst and release egg (Ovulation)
ovulation
estrogen
Ovarian cycle – The follicle
Women are born with ~450,000 egg containing follicles. It is believed that no new eggs are produced after birth, but it is known that other mammals can produce eggs after birth so it may be possible.
Women can release up to 500 eggs during a lifetime.
- Primary oocyte is an immature egg that is suspended at prophase I of meiosis I.
Ovarian cycle – The follicle
Primordial follicle consists of primary oocyte and layer of cells nourishing oocyte. Primordial follicle
Ovarian cycle – The follicle
Women are born with ~450,000 egg containing follicles. It is believed that no new eggs are produced after birth, but it is known that other mammals can produce eggs after birth so it may be possible. Women can release up to 500 eggs during a lifetime.
- Primary oocyte is an immature egg that is suspended at prophase I of meiosis I.
- FSH + LH stimulate Primordial follicle to begin maturing
- Cells around oocyte begin duplicating
- Oocyte completes Meiosis I with most cytoplasm distributed to 1 of the 4 eggs produced and called the secondary oocyte. The remaining eggs become polar bodies and degenerate.
Ovarian cycle – The follicle
- As the follicle matures its cells begin releasing estrogen.
- As estrogen levels increase Pituitary releases a burst oh LH.
- In response to the elevated LH the follicle bursts releasing the egg from the ovary into the fallopian tube.
Estrogen
LH
Ovarian cycle – The follicle
- After releasing the egg the follicle becomes a “corpus luteum”.
- The corpus luteum begins producing progetsrone, which prepare the uterus & endometrium for pregnancy.
- If no pregnancy occurs the corpus luteum degenerates and stop producing progesterone.
Corpus Luteum
Progesterone
Fig. 38.21, p. 663
Ovulation
hypothalamus anterior pituitary FSH LH
midcycle peak of LH (triggers ovulation) Blood levels of FSH ( purple ) and LH ( lavender ) FSH LH LH
estrogens progesterone, estrogen
estrogens progesterone, estrogen
Blood levels of estrogens ( light blue ) and progesterone ( dark blue )
growth of follicle
FOLLICULAR PHASE OF MENSTRUAL CYCLE
LUTEAL PHASE OF MENSTRUAL CYCLE
menstruation
endometrium of uterus
Days of one menstrual cycle (using 28 days as the average duration)
hypothalamus
anterior lobe of pituitary gland ovulation corpus luteum
GnRH
Figure 38. from page 664 of your text
Fate of the egg
1. If the egg is fertilized in the fallopian tube and
successfully implants into the endometrium of the
uterus, The embryo begins producing Human
Chorionic Gonadotropin (HCG).
2. HCG maintains the Corpus Luteum, which results
in the continued release of progesterone, which
maintains the uterus during pregnancy.
Pregnancy test kit
1. Purify HCG
2. Inject purified HCG into mouse
3. Collect blood serum from mouse
4. Purify HCG specific antibodies
5. Attach antibodies to color producing proteins.
6. Place antibody complex on a test platform.
7. When urine of pregnant women comes into contact with
platform HCG binds to the antibody complex producing a
color.
zona pellucida follicle cell granules in cortex of cytoplasm
nuclei fuse
FERTILIZATION
OVULATION
oviduct
ovary uterus opening of cervix vagina sperm enter vagina
Figure 38. from page 665 of your text
Sperm Blocked at Fertilization Membrane
Unsuccessful
Sperm on Outside
Surface of Egg
Pregnancy
uterus
ovary
oviduct
endometrium
IMPLANTATION
FERTILIZATION
inner cell mass
(see next slide)
Figure 39. from page 666 of your text
Fig. 38.28, p. 671
endometrium
uterine cavity
blastocoel
Trophoblast (surface layer of cells of the blastoyst)
inner cell mass
start of amniotic cavity (^) start of embryonic disk
start of yolk sac
blood-filled spaces
start of chorionic cavity
DAYS 6-7 DAYS 10-
DAY 14 DAY 12
yolk sac
chorionic chorionic cavity villi
chorion
amniotic cavity
connecting stalk
paired neural folds future brain
neural somites groove
DAY 15
primitive streak
yolk sac
embryonic disk
amniotic cavity
chorionic cavity
DAYS 24-
DAYS 18-
Fig. 38.29, p. 672
pharyngeal arches
yolk sac
connecting stalk
embryo
forebrain future lens
pharyngeal arches developing heart upper limb bud somites neural tube forming lower limb bud tail Figure 38. from page 674 of your text
Week 4
Weeks 5-
head growth exceeds growth of other regions
retinal pigment future external ear upper limb differentiation (hand plates develop, then digital rays of future fingers, wrist, elbow start forming) umbilical cord formation between weeks 4 and 8 (amnion expands, forms tube that encloses the connecting stalk and a Figure 38.31 foot plate duct for blood vessels) from page 674 of your text
1. final week of embryonic
period; embryo looks
distinctly human compared
to other vertebrate embryos
2. upper and lower
limbs well-formed;
fingers and then toes
have separated
3. primordial tissues of
all internal, external
structures now developed
4. tail has become stubby
Week 8
Figure 38. from page 675 of your text
WEEK 38 (full term)
Length:
Weight:
50 cm (20 inches)
3,400 grams (7.5 pounds)
Figure 38. from page 675 of your text
Birth Control Options
Prevent fertilization
Prevent ovulation
Block implantation
Contraception Failure Rates
• Implants and injectables 2-4%
• Oral contraceptives 9%
• Diaphragm and cervical cap 13%
• Male condom 15%
• Periodic abstinence 22%
• Withdrawal 26%
• Spermicides 28%
Sexually Transmitted
Diseases (STDs)
1. Worldwide epidemic of STDs
2. Women are most affected
3. Can cause infertility, pain,
and even death
Causative Agents of STDs
1. Viruses
- AIDS (HIV)
- Genital herpes
( Herpes simplex )
(HPV)
1. Bacteria
( Neisseria
gonorrhoeae )
( Trepnema
pallidum )
infections
AIDS
1. Virus attacks T cells
2. Immune system is destroyed
3. Opportunistic infections and cancers
eventually cause death
4. Treatment is available, but there is no
vaccine and no cure
AIDS Test
1. Should know HIV status of potential
partner
2. A person can test negative and still have
and transmit the virus
3. Test detects antibodies that appear weeks
to months after infection
Genital Herpes
1. Caused by Herpes simplex Type II
2. Periodic eruption of small, painful blisters
on genitals
3. Infection requires contact with fluid from
these sores
4. Antiviral drugs can reduce pain but there is
no cure
Human Papillomaviruses
1. HPV can cause bumplike warts on the
genitals and anus
2. One strain, 16 HPV, does not cause
symptoms
3. It can lead to cancers of cervix, vagina,
vulva, penis, and anus
4. There is no cure
Gonorrhea
1. Caused by the bacterium Neisseria
gonorrhoeae
2. Females often symptom-free in early stages,
males discharge pus
3. Can cause sterility if untreated
4. Can be cured with antibiotics
Syphilis
1. Caused by the spirochete Treponema
pallidum (a kind of bacterium)
2. Early symptoms are painless chancres; later
an extensive rash
3. In some, immune response to infection
causes damage to brain and spinal cord
4. Passage from mother to infant can cause
stillbirth, infection of newborn
Chlamydial Infections
1. Most common reported STD in U.S.
2. A variety of diseases caused by bacterium
3. Leads to inflammation of cervix in female,
burning urination in both sexes
4. In females, can spread to uterus and
oviducts to cause PID
Pelvic Inflammatory
Disease (PID)
1. Complication of many bacterial STDs
2. Bacteria infect uterus, oviducts, ovaries
3. Symptoms include bleeding, vaginal
discharge, pain in lower abdomen
4. Increases likelihood of ectopic pregnancy
5. Can cause sterility
