Why Men Pee Standing Up
God was just about done creating humans, but he had two parts
left over and couldn't quite decide how to split them between Adam
and Eve. He thought he might just as well ask them.
He told them one of the things He had left was a thing that would
allow the owner to pee while standing up. "It's a very handy thing,"
God told them, "and I was wondering if either one of you had a
preference for it."
Well, Adam jumped up and down and begged, "Oh, please give
that to me! I'd love to be able to do that! It seems like just the sort
of thing a man should have. Please! Pleeease! Give it to me!"
On and on he went like an excited little boy. Eve just smiled and
told God that if Adam really wanted it so badly, he could have it, so
God gave Adam the thing that allowed him to pee standing up.
Adam was so excited he just started whizzing all over the place first on the side of a rock, then he wrote his name in the sand, and
then he tried to see if he could hit a stump ten feet away - laughing
with delight all the while.
God and Eve watched him with amusement and then God said to
Eve, "Well, I guess you're kind of stuck with the last thing I have
left."
"What's it called?" asked Eve.
"Brains," said God.
ZOOLOGY
Reproduction
Professor Geoff Shaw
Department of Zoology
g.shaw@zoology.unimelb.edu.au
• KLES5: Chapter 20;
Chapter 28 esp gonads and HPG axis
section pp 693-695, fig 28.11
• KLES4: Chapter 19;
Chap 27, esp p 647-648, Fig 27.10
ZOOLOGY
Copyright Notice
ZOOLOGY
Reproduction-Fundamental to life
• Reproduction with and without sex
• Reproduction and life-history strategies
• Structure and function of reproductive
systems
ZOOLOGY
Sexual vs Asexual Reproduction
• What is Sex?
– A messy mechanism for getting eggs and
sperm together…
• Asexual reproduction
– reproduction without using sperm and eggs
ZOOLOGY
Sexual Reproduction
•
•
•
•
Origin of the word “Sex”:
Needs two sexes
1350–1400; ME < L sexus “division” “separated”
Meiotic cell division
Sperm – small, motile
Offspring a combination
Common strategy among both
invertebrates and vertebrates
• requires mechanisms to get sperm and
egg together  fertilization 
development
4-cell wallaby
embryo with sperm
ZOOLOGY
in egg coats
Egg –
large, non motile
photos by Geoff Shaw
Meiosis
• Specialised form
of cell division
– haploid gametes
(eggs and sperm)
– gametes fuse to
form a new diploid
individual
diploid- 2n
zygote
haploid- 1n
n
2n
n
fertilization
2n
individual
germ stem
cells
2n
male
2n
female
sperm
n
n
n
n
n
n
n
meiosis n
ZOOLOGY
egg
Asexual Reproduction
• Mitotic cell division
• Offspring genetically identical to parents
• Common strategy among invertebrates
but also seen in some vertebrates
budding
(eg hydra)
regeneration
eg starfish
cell fission
(common in unicellular organisms)
ZOOLOGY
KLES5 Figs 18.1-3
Variations on a theme…
• Hermaphrodites
– same individual produces both
sperm and eggs
– may be able to self-fertilize
but common for sperm and eggs
to be made at different times
– may involve sex-change
eg wrasse (see KLES4 19.7)
ZOOLOGY
Hermaphroditus
Variations on a theme…
• Parthenogenesis
– make egg via meiosis
– egg activates and develops
without a sperm fertilizing it.
eg Aphids
ZOOLOGY
Reproductive Strategies
lots of cheap-to-make
offspring
given little care
few offspring, with
heavy investment
in development
and care
ZOOLOGY
enough offspring
survive to provide
next generation
Which is best?
coral vs human
see KLES4 Box 19.4
ZOOLOGY
http://www.photolib.noaa.gov/sanctuary/images/big/sanc0417.jpg
photo Yves Picq via
http://en.wikipedia.org/wiki/
File:Namibie_Himba_0703a.jpg
Antechinus – a big bang strategy
females
juveniles
lactation
births
mating
sperm in testes
male die off
males
juveniles
month of year
ZOOLOGY
photos by G Shaw
Costs and benefits in reproduction
Benefits
Mating displays
• attracting mates
Harems
• access to mates
external fertilization • physiology simple
internal fert’n
• make fewer eggs/sperm
viviparity
• high survival of young
post natal care
• high survival of young
ZOOLOGY
Costs
• attracting predators
• male fighting
• high loss of gametes
• complex physiology
• risk to preg. mother
• huge investment by
parents
Basic design of Reproductive Tracts
testis
sperm production
hormones
accessory organs
 bulk of semen
lubrication
assist fertilization
ZOOLOGY
Ovary
Ducts
convey sperm
maturation
storage
External genitals
transfer gametes
(eggs and sperm)
egg production
hormones
Ducts
convey eggs
add protective coats
?sperm and fertilization
?maturation of embryo
gonads: testes and ovaries
gametes: eggs and sperm
ducts: regionally specialised for specific roles
genital: relating to the reproductive system
external genitals: “naughty parts”
male toad urogenital tract
fat bodies
kidney
testis
efferent ducts
urogenital duct
seminal vesicle
bladder
rectum
cloaca
ZOOLOGY
male mouse reproductive tract
kidney
fat
seminal
vesicle
vas deferens
testis
bladder
epididymis
penis
ZOOLOGY
prostate (hidden
by bladder)
Human Male Reproductive Tract
Bladder
Box 18.1
Vas deferens
Seminal
vesicle
Prostate
Epididymis
Scrotum
Testis
(plural: Testes)
ZOOLOGY
Urethra
Penis
female toad urogenital tract
NOTE: huge number of eggs
oviducal
funnel
oviduct
ovary
kidney
ovisac
rectum
cloaca
ZOOLOGY
female mouse urogenital tract
utero-ovarian blood vessels
fat pad
ovary
oviduct (Fallopian tube)
uterine horn
bladder
cervix (under bladder)
vagina (not visible as it
passes through the pelvis)
vaginal opening
ZOOLOGY
kidney
Human Female Reproductive Tract
Oviduct / Fallopian tube
Ovary
(Ovaries)
Uterus
Cervix
Egg
Vagina
ZOOLOGY
Box 18.1
Follicle
External vs Internal Fertilization
• External fertilization.
– eg toad – no specialised external genitals needed,
but males have nuptial pads on forelimbs to help
grasp the female in Amplexus
– aquatic environment
– usually large numbers of gametes
• Internal Fertilization
– requires specialization of the external genitalia to
allow sperm transfer, eg penis
– works in dry environments
– needs fewer gametes
– prerequisite to viviparity (internal gestation, birth
of live young)
ZOOLOGY
Amplexus
Cost:
Time
and
Energy
of
mating
ZOOLOGY
behaviour
Amplexus: Male holds onto female using special foot pads
KLES4 19.26
Other reproductive organs
• mammary glands
– nutrient transfer in mammals
• placenta
– nutrient transfer in species with internal
development
– hormone production
• brain
– reproductive behaviour
– hormone control
ZOOLOGY
What do I expect you to learn from this lecture?
• Reproduction  continuation of life
• Variety of patterns of reproduction
– costs and benefits of different patterns
• Asexual reproduction
– mitotic; clones; no genetic recombination
• Sexual reproduction
– meiotic; genetic recombination; unique offspring.
– characteristics of eggs and sperm
– anatomy of reproductive tracts
ZOOLOGY