Biology 30
Human Reproduction &
Development
 Anatomy
of the Male and Female Reproductive
Systems
 Gamete Formation
 Hormonal Control of Reproduction
 Conception, Pregnancy, Development, Birth
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Biology 30
Male Reproductive Anatomy
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You solve the problem.

“Recently I have experienced my right testicle
slipping upwards into my body and
‘disappearing’. It can be felt through the skin,
and then can be slid back down. The only pain
is a dull ache that ensues. It seems to require
some pressure on the scrotum to occur, such as
my wife being ‘frisky’. Is there a term and/or a
treatment for this? Is it serious?”
December 7, 1999
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Anatomy of the Male
Reproductive System

External genitalia
– Penis and Scrotum

Internal Reproductive Organs
– Pair of gonads
 Produce gametes (sperm cells)
 Produce hormones
– Accessory glands
 Secret products essential to sperm movement
– Set of ducts
 Carry sperm and glandular secretions.
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Anatomy of the Male
Reproductive System

Penis
– Composed of 3 cylinders of spongy tissue.
– During sexual arousal, tissue fills with blood
from the arteries
 The increasing pressure seals off the veins that
drain the penis
– Result = penis engorges with blood = erection
– The tip (Glans) is covered by a fold of skin
called the foreskin, which may be removed by
circumcision
 A tradition with religious roots.
 No verifiable health or hygienic advantage.
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Anatomy of the Male
Reproductive System

Scrotum
– Sac which contains testes
– Regulates temperature of testes by
contraction of cremaster muscle.
 Cold = contracts
– Brings testes close to body to warm up.
 Warm = relaxes
 Goal = keep testes 3o below normal body
temperature.
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Anatomy of the Male
Reproductive System

Testes
– Stored in scrotum
 Before birth, testes develop in the abdomen and then
migrate down a canal into scrotum around the time of birth.
– Sperm producing organ
 Made in tightly coiled tubes called seminiferous tubules
inside testes
 Sperm produced is not fully mature when it leaves testis (not
motile yet)
– Source of male hormone testosterone
 Made by interstitial cells scattered between the seminiferous
tubules
– Deposits sperm into epididymis
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Anatomy of the Male
Reproductive System

Epididymis
– Coiled tubes
– About 6 meters long!!
– Posterior to the testis
– Stores sperm
– Site of further sperm maturation
 Gains motility
– Contracts during ejaculation, expelling sperm
into vas deferens
– Sperm can be store here for months
 If not ejaculated, will eventually be phagocytized
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Anatomy of the Male
Reproductive System

Vas Deferens
– Muscular tubes that carry sperm from
epididymis to ejaculatory duct (and
eventually the urethra)
 peristalsis
– Urethra drains both the excretory system and
the reproductive system
 Not the case in females
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Anatomy of the Male
Reproductive System

Ejaculatory Duct
– Connects seminal vesicle to urethra
– Passes through prostate gland
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Anatomy of the Male
Reproductive System

Seminal Vesicle
– Lies below and behind bladder
– Secretes thick, clear fluid into ejaculatory duct
 60% volume of semen (the fluid that is
ejaculated)
 Alkaline – to neutralize acidic pH of vagina
 Fructose – used for energy by sperm
 Prostaglandins – chemical messengers which,
once in female, stimulate uterine peristalsis to help
move semen up the uterus
 Proteins – cause semen to coagulate after it is
deposited in the female, making it easier for the
uterine contractions to move the semen
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Anatomy of the Male
Reproductive System

Prostate Gland
– Doughnut shaped gland which surrounds
urethra
– Secretes thin milky fluid into urethra
 20% of seminal volume
 Liquefy the semen – prevents sperm from
clumping together
 Alkaline – continues to neutralize acid from
residual urine in urethra and natural acidity of
vagina
Prostate
Source of most common medical problems
of men over 40. Benign enlargement in
over ½ of all men in the age group.
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Anatomy of the Male
Reproductive System

Cowper’s Gland (Bulbourethral Gland)
– Pair of small glands along urethra, below the
prostate
– Secrete viscous fluid before emission of
sperm & semen
 Thought to lubricate penis and vagina
– Released before ejaculation
 Fluid does contain some sperm
 One factor in the high failure rate of the
“withdrawal method” of birth control.
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Anatomy of the Male
Reproductive System

Vasectomy
– Incision through scrotum
– Cut and tie off vas deferens
– Sperm is still produced but can’t get out
– Phagocytized
– Increased risk of prostate cancer
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Anatomy of the Male
Reproductive System

Passageway from testes to outside
1. Multiple seminiferous tubules

2.
3.
4.
5.
6.
site of spermatogenesis
Single tubed epididymis
Vas deferens
Seminal vesicle
Ejaculatory duct
Urethra
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Anatomy of the Male
Reproductive System

For Your Information
– Volume of ejaculation = 2.75 ml
– pH = 7.2 – 7.6
– 50 – 150 million sperm per ml.
– Only a few sperm reach the egg
– Average sperm count has decreased from 113
million/ml to 66 million/ml in past 40 years.
– Infertility = <20 million/ml
 Factors leading to infertility are environmental
toxins, estrogens in meat, radiation,pesticides,
marijuana, alcohol
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Solution to the medical
problem.
Remember that before birth, the testes develop
in the abdomen, and then migrate down into
the scrotum at birth. The pathway they
follow through the layers of the abdominal
wall on each side is called the inguinal canal.
Usually, when the testes have completed
their descent they remain permanently within
the scrotum from that time on. The slightly
lower temperature in the scrotum is more
favorable to sperm production after puberty.
Slender bundles of muscle fibers derived from
the middle layer the abdominal muscle are
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Solution to the medical
problem.
drawn into loops around the descending testis
and form what is know as the cremaster
muscle. During sexual arousal, the smooth
muscle of the scrotum contracts too. As a
result, the testes are transiently held in a
more protected position during sexual
intercourse. It is possible that your right
testis has remained more mobile that usual,
and is drawn back partially in the to inguinal
cal by contraction of the cremaster muscle
during sexual activity. This is referred to as
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Solution to the medical
problem.
a “retractile testis”. If you at all concerned
about this possibility, it will be worthwhile
visiting your doctor to discuss the situation
and whether or not any treatment is required.
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Labelling Diagram
1.
2.
3.
4.
5.
6.
7.
Pubic Bone
Seminal Vesicles
Rectum
Prostate Gland
Cowper’s Gland
Anus
Vas Deferens
(sperm duct)
Epididymis
9. Testes
10. Urethra
11. Penis
12. Scrotum
13. Head of Penis
(Glans)
14. Foreskin
15. Bladder
8.
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Biology 30
Female Reproductive
Anatomy
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Anatomy of the Female Reproductive System
Consists of:
 External genitalia

– Two sets of labia that surround the clitoris
and vaginal opening

Internal Reproductive Organs
– A pair of gonads (ovaries)
– A system of ducts and chambers to
 Conduct the gametes
 House the embryo and fetus
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Anatomy of the Female Reproductive System

Ovaries
– Lie in abdomen, below most of the
digestive system
– Enclosed in a tough protective capsule
– Produces eggs (follicles)
– Produces female sex hormones
1. Estrogen
2. Progesterone
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Anatomy of the Female Reproductive
System

Follicles
– Consists of one egg cell surrounded by
layers of follicle cells.

Nourish and protect the developing egg cell
– All of the 400,000 follicles a woman will ever
have are present at birth.


Only a few hundred will be released during a
woman’s reproductive years
One (very rarely 2 or more) follicle matures and
releases its egg during each menstrual cycle
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Anatomy of the Female Reproductive
System

Follicles
– Follicle cells release the primary female sex
hormone… estrogen.


Secondary sex characteristics, wider hips, more body fat,
Necessary for breast development
– At ovulation, the egg “explodes” out of the
follicle leaving behind the follicular tissue


This grows into a solid mass called a Corpus Luteum
– Secretes progesterone (necessary for pregnancy)
If fertilization does not occur, the corpus luteum
disintegrates and a new follicle matures the next month.
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Anatomy of the Female Reproductive
System

Oviduct
–
–
–
Fallopian tube
Conducts eggs to the uterus
Fertilization occurs here

–
–
If embryo grows here = ectopic pregnancy
The ovary and oviduct don’t actually touch.
The egg is released into the abdominal cavity and is
“sucked” into the oviduct.
 Oviduct has fingers called “fimbrae” and hairs
called “cilia” that vibrate and sweep the egg into
the tube by swishing body fluids towards itself
 These cilia also help move the egg towards the
uterus
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Anatomy of the Female Reproductive
System

Uterus (womb)
–
–
–
–
Houses and nurtures the developing fetus
Oviducts enter at the top
Cervix (opening) at the bottom
The lining is called the endometrium




Richly supplied with blood vessels
Varies in thickness depending on the stage of the
menstrual cycle
Controlled by hormones
2 Layers
– Basal layer = stable, does not change thickness
– Functional layer = changes thickness with menstruation
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Anatomy of the Female Reproductive
System

Vagina
–
–
–
–
–
–
Birth canal
Average = 7.5 cm in length
pH = 4-5
Upper end closes at cervix
Receives penis during sexual intercourse
Elastic to facilitate sexual intercourse and
birth
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Biology 30
Gamete Formation
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Gamete Formation

Need
–
The human body cell contains 46 chromosomes that
are paired together


–
If 2 diploid (means 46 chromosomes) cells fuse the
result would be …


–
–
23 pairs
Called diploid cells
92 chromosomes (46 pairs)
Chromosome number would increase exponentially
Sperm and egg must contain 23 chromosomes each
in order to maintain appropriate chromosome count
Haploid = ½ the normal chromosome count
23 chromosome sperm +23 chromosome egg = 23 pairs
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Gamete Formation

Spermatogenesis
– Each ejaculation = 400 million sperm
– Males can ejaculate daily without loss of
fertility
– Occurs in the testes
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Gamete Formation
Spermatogenesis
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Gamete Formation
Spermatogenesis
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Gamete Formation -1.
2.
3.
4.
The walls of the seminiferous
tubules consist of diploid
spermatogonia, stem cells
that are the precursors of
sperm.
divide by mitosis to produce
more spermatogonia
The Meiosis of each
spermatocyte produces 4
haploid spermatids.
These then differentiate into
sperm, losing most of their
cytoplasm and gaining
motility in the process.
In epididymis


Sperm nourished by sertoli
cells (in seminiferous tubules)
Whole process takes 70 days
Spermatogenesis
Gamete Formation -Takes place in ovaries
2. Primary Oogonium develop
into oocytes before birth
3. Oocytes complete maturation
one at a time & once a month
during reproductive years
4. Primary oocyte grows larger
and begins meiosis
5. Forms a secondary oocyte
and first polar body
6. After fertilization, secondary
oocyte completes meiosis and
become 1 egg and second
polar body.
Oogenesis
1.
Before Birth
Once a month
If Pregnant
Recap of Follicles

Follicles
–
–
Consists of one egg cell surrounded by layers of
follicle cells.
Nourish and protect the developing egg cell
– Follicle cells release the primary female sex
hormone… estrogen.
– At ovulation, the secondary oocyte “pops”
out of the follicle leaving behind the
follicular tissue


This grows into a solid mass called a Corpus Luteum
– Secretes progesterone (necessary for pregnancy)
If fertilization does not occur, the corpus luteum
disintegrates and a new follicle matures the next month.
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Review
Complete Lessons 1 & 2 from
your Unit Objectives Package
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