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Human Reproduction
• “If you study the divorces, as we have had
to do in these past years you will find…sex
is the first (reason). They did not get along
sexually. They may not say that in court.
They may not even tell that to their
attorneys but that is the reason.
Spencer W. Kimball,
(The teachings of Spencer W. Kimball, Salt lake city: Bookcraft, 1982, pg 46)
Sex Organs
• Primary sex organs:
– Are the gonads i.e.… Testes and Ovaries
– Produce the gametes and sex hormones.
• Accessory sex organs
– Ducts that provide transport for gametes
– Glands that provide nutrients
Male
Reproductive
System
Testes
•
•
Formed in abdominal cavity.
Cryptorchidism “hidden
testes”
– Sterility if not corrected
in childhood
– Subject ot tumor
formation
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
Testes
• Cutting inside the
testes you would find
125 meters of interconnecting tubes
called
• Seminiferous tubules
Seminiferous tubules
• The location in which
germ cells undergo
meiosis to become
sperm.
Spermatogenesis
• Sperm are derived from 2n
spermatogonium germ cells.
• As these cells divide they are
pushed away from the wall into
the tubules interior.
• Spermatogenesis takes about 910 weeks
• Spermatogenesis is controlled
by sertoli cells.
• Seritoli cells also provide
nourishment for the developing
sperm cells.
Sertoli cell
Spermatogonium
Germ cell
Sperm
• The sperm cell can be divided
into three parts: tail, midpiece
and head.
• The tail is a long singular
falgella
• Midpiece moves the flagella
and has many mitochondria
• Head contains DNA
– Acrosome contains digestive
enzymes which are release to
unable the sperm to work its
way through the zona palucida.
acrosome
Head
Tail
Midpiece
Testosterone
• Are produce by cells inside the testes called
Leydig cells
• Functions of Testosterone
– Development of sperm
– Development of secondary sex characteristics
• Traits that are distinctly associated with maleness
but do not play a direct role in reproduction
example: voice, shoulder, muscle, body hair.
Epididymis
Epdidymis
• A duct located on top
of the testis
• Functions as a place in
which sperm are
stored and where they
mature.
Epididymis
Vas Deferens
• One of a pair of ducts for
rapid transport of sperm
• Vasectomy is a common
surgical method of
sterilizing males.
• Males ejaculate without
semen
• Semen is the glandular
secretion which become
mixed with sperm
Vas Deferens
Seminal Vesicle
• One of a pair of glands
that secrete fructose
sugar as part of the
semen
• Makes the semen very
viscous
Seminal vesicle
Prostate gland
• Contributes prostate
fluid, to the semen.
• Prostate fluid is highly
alkaline to off-set the
high acidity of the
vagina.
Prostate gland
Bulbourethral glands
Upon sexual excitement and
prior to ejaculation, these
glands are stimulated to
secrete a mucoid substance
which coats the lining of the
urethra to neutralize the pH
of the urine residue and
lubricates the tip of the
penis in preparation for
sexual intercourse
Bulbourethral
(Cowper’s)
gland
Urethra
• Serves as a common
tube for both the
urinary and
reproductive systems.
Urethra
Penis
• Composed of erectile tissue
which contains numerous
vascular spaces that become
engorged with blood.
• Sexual arousal leads to an
erection in which the penis
becomes longer, wider and
firmer.
• An erection is absolutely
necessary in order to have
normal sexual intercourse.
Penis
Erectile Dysfunction
• Impotence is the inability of a man to have
an errection.
– Causes may include
• Injury to nerves, arteries, are muscles
• Medications for high blood pressure, antihistamines,
and depression
• Psychological factors such as anxiety, guilt,
depression, and fear of sexual failure cause up to
20 % of all cases
Hormonal control of
male reproduction
Fig. 45.5, p. 787
Female Reproductive System
Primary Sex Organ
The Ovaries
Ovaries
• Each ovary produces
an ovum about every
other month
• The ovaries stagger
their production so
that one ovary
produces an ovum one
month and the other
produces it the
following month.
Menstrual Cycle
• The menstual cycle is a recurring reproductive cycle, which
last on average 28 days. Durring this time an oocyte is
released from one of a pair of ovaries, and the endometrial
lining of uterus is primed for pregnancy.
• In the event that the oocyte does not become feritilized
endomytrial tissue along with blood from the uterus will
flow out through the vaginal canal (menstruation).
secondary oocyte
Ovulation.
Mature follicle ruptures
and releases the
secondary oocyte and
the first polar body.
first polar body
antrum
A corpus luteum forms
from remnants of the
ruptured follicle.
A primordial follicle;
meiosis I has been
arrested in the primary
oocyte inside it.
primordial
follicle
When no pregnancy
occurs, the corpus
luteum degenerates.
Fig. 45.7b, p. 790
Follicle Production
Ovulation
Mature follicle
Granulosa
cells
A primordial follicle;
meiosis I has been
arrested in the primary
oocyte inside it.
• At birth, a female will have all
the oocytes she will ever have.
• At puberty a single oocyte will
mature inside a follicle.
• The follicle consist of granulosa
cells that produce estrogen and
an oocyte.
• From day 1 through day 13 the
follicle grows producing more
and more estrogen.
• Estrogen causes the production
of Follicle stimulating hormone
(FSH).
• FSH cause the follicle to grow
which in turn produces more
estrogen (positive feedback)
Ovulation
• In Large amounts, estrogen
also stimulates the production
of Luteinizing hormone (LH).
• LH causes the follicle to
rupture and the oocyte to burst
out. This process is called
“ovulation”
• In a 28 day menstrual cycle
ovulation occurs on day 14.
• It is at this time that a woman is
most likely to become
pregnant.
Development of the Corpus Luteum
• After ovulation, the granulosa
cells in the ruptured follicle
come together to form a
structure called the corpus
luteum.
• The corpus luteum’s function
is to secretes progesterone.
• Progesterone keeps the uterine
lining in place for
implantaiton of the egg.
Ovarian Cyst
Fertilization
• The oocyte is released and
is taken up by the oviduct.
• The cells lining the
oviduct are ciliated and
move the oocyte toward
the uterus
• Successful Fertilization of
the oocyte occurs in the
upper portion of the
oviduct
Fertilization cont.
• Out of about 200 million sperm only
about 50 – 100 reach the egg.
• When sperm contact the oocyte they
release enzymes that clear a path
through the zona pellucida.
• As soon as the first sperm penitrates
the plasma membrane the zona
pellucida instantly hardens keeping all
other sperm out.
• The fusion of the sperm and egg
create a zygote. The zygote is 2n.
Zona pellucida
Oviducts
• As the zygote travels down the oviduct it undergoes cleavage.
• Cleavage is the multiplication and division of cells in the
zygote without the zygote growing in size.
• The zygote stays the same size as the cells divide into smaller
and smaller units
• By the fifth day the zygote is a ball of cells called a
blastocyst.
• After 7-10 days old the blastocyst implants itself in the
uterus.
The Uterus
• consists of 2 major layers: the
myometrium and the
Endometrium.
– Myometrium is a large muscle
layer that is able to contract for
long periods of time.
– Endometruim is the inner mucosal
lining that thickens and sloughs off
a periodic cycles during the
menstral cycle. It is also the layer
where the blastocyst implants.
Myometrium
Endometrium
Cervix
Blastocyst
• The Blastocyst consist of two
different cell types that form
in inner and outer layer.
Endometrium
Trophoblast
• The inner layer of cells
produce the embryo.
• The outer layer of cells called
the trophoblast implant into
the uterine wall and produce
the placenta.
Inner cell mass
Ectopic pregnancy
• If the blastocyst implants somewhere
outside the uterus it is called an ectopic
pregnancy.
– Implantation in the uterine tube is called a
tubule pregnancy. This results in a medical
emergency.
– Implantation can also occur in the intestines or
the walls lining the abdominopelvic cavity
MATERNAL
CIRCULATION
maternal
blood vessels
movement of
solutes to and
from maternal
blood vessels
(arrows)
FETAL
CIRCULATION
embryonic
blood vessels
umbilical cord
blood-filled space
between villi
chorionic villus
tissues
of uterus
fused amniotic and
chorionic membranes
Fig. 45.13a, p. 797
4 weeks
8 weeks
12 weeks
appearance of the
placenta at full term
Fig. 45.13b, p. 797
OVIDUCT
OVARY
UTERUS
MYOMETRIUM
ENDOMETRIUM
urinary bladder
opening of cervix
urethra
CLITORIS
LABIUM MINOR
LABIUM MAJOR
VAGINA
anus
Fig. 45.6b, p. 789
Vagina
• Tube that receives sperm.
• The lower part of birth
canal.
• Muscular with folds so
that is can extend.
• Sexual arousal stimulates
mucus secreting glands
that lubricate the vagina
in preparation for sexual
intercourse.
Vagina
Vulva
• Consists of
– Labia major
– Labia minor
– Clitoris
Clitoris
Labia minor
Labia major
secondary oocyte
surrounded by
follicle cells
surface of
ovary
Fig. 45.8, p. 791
hypothalamus
GnRH
anterioir pituitary
FSH
LH
midcycle peak of LH (triggers ovulation)
hypothalamus
Blood levels of
FSH (purple) and
LH (lavender)
anterior lobe
of pituitary
gland
FSH
LH
growth of follicle
estrogens
LH
ovulation
corpus luteum
progesterone, estrogen
Blood levels of estrogens
(light blue) and
progesterone (dark blue)
endometrium
of uterus
Days of one menstrual cycle (using
28 days as the average duration)
estrogens
progesterone, estrogen
menstruation
Fig. 45.9, p. 792
FOLLICULAR PHASE OF
MENSTRUAL CYCLE
LUTEAL PHASE OF
MENSTRUAL CYCLE
Bishop’s Handbook