1. BIOL10004 Animal Development
Geoff Shaw
Animal Development
Professor Geoff Shaw
School of BioSciences
Ref:
KLES4, Ch 19 pp ;
Ch 20 pp
KLES5 Ch 20 pp
Ch 21 pp ; ; 505

2. Copyright Notice

3. Vertebrate Egg Variation
Echidna
(G Shaw)
1 mm
Frog
1 mm
10 mm
1 mm
chick
mouse
zebrafish

4. Mammalian Sperm Variation
KLES4 Fig 19.5, KLES5 Fig 20.5

5. Gametogenesis: Spermatogenesis
BIOL10004 Animal Development
Gametogenesis: Spermatogenesis
Stephen Frankenberg
Mitotic
divisions of
spermatogonia
(continues through life in mammals)
First meiotic
division
Second meiotic
division
DNA condensation
formation of tail, etc
spermatogonium
never run out of sperm
Primary
spermatocyte
Secondary
spermatocyte
Spermatids
Sperm
KLES4 Fig 19.20, KLES5 Fig 20.20

6. Gametogenesis: Oogenesis
Oogonia proliferate during fetal development, then enter meiosis
Primary oocytes remain dormant until puberty
Some primary oocytes resume meiosis at each cycle
Sperm
KLES4 Fig 19.20, KLES5 Fig 20.20

7. Differences in meiosis between male & female gametogenesis (in mammals)
Males
mitosis continues through reproductive life
continued production of spermatocytes
meiotic spermatogonium  4 haploid sperm
Females
eggs end mitosis during development and enter meiotic arrest
finite number of eggs, numbers decline throughout life  menopause
meiotic egg  1 egg, 2 polar bodies

8. Fertilization in sea urchin
Centriole
Acrosomal
Vesicle
Egg jelly
coat
Vitelline
membrane
Hydrolytic
enzymes
Acrosome
reaction
Sperm nucleus
(pronucleus)
Centriole
Acrosomal
process
Fertilization
cone
Egg plasma membrane *
Egg
activation
Egg cytoplasm
adapted from KLES ; KLES

9. Fertilization Contribution of sperm and egg to the zygote: Sperm:
see
Contribution of sperm and egg to the zygote:
Why 1 not 4
haploid eggs?
Sperm:
A haploid pronucleus
Centriole (most species)
Egg:
Nutrients
Cytoplasm and cell machinery
Cytoplasmic Factors that will control
early stages of development

10. Development
???
Fertilized human egg

11. Processes in development
simple structures
simple rules
Complexity
proliferation
death
movement
shape
cellular differentiation

12. Development process fertilization cleavage blastulation gastrulation
neurulation
organogenesis
stage
fertilized egg / zygote
cleavage stage
blastula / blastocyst
gastrula
neurula
fetus

13. Cleavage to blastula (frog)
Animal
Pole
yolk
Vegetal Pole
KLES4 20.4; KLES5 21.4

14. Cleavage to blastula (mouse)
Blastocyst
Inner cell mass cells
Trophoblast cell
Blastocoel
(cavity)
fetus
placenta and
fetal membranes
KLES4 20.6; KLES5 21.6

15. Gastrulation - toad
KLES4 20.8

16. "It is not birth, marriage, or death, but gastrulation which is truly the most important time in your life.“
Lewis Wolpert

17. Outcomes of gastrulation
formation of 3 germ layers
ectoderm, mesoderm, endoderm
Establish body plan
3 axes  head-tail; dorsal-ventral; left-right
New body cavity  archentron
ectoderm
dorsal
archenteron
tail
mesoderm
endoderm
right
head
ventral
left
KLES4 20.8

18. Derivatives of germ layers
endoderm
-gut lining and derivatives
mesoderm – muscles, blood, organs
ectoderm- skin and nervous system
Germ cells
How are these
organs generated?

19. neurulation c a b d Neural folds Neural folds meet Neural plate
notochord
(induction)
Dorsal skin
Neural tube
Neural groove b d
KLES

20. Neurulation neural tube notochord developing coelom ectoderm mesoderm
endoderm
gut

21. Organogenesis
localised interactions between cells induce formation of new cell types
cells change shape and character and may migrate along specific pathways
different cell types associate in specific patterns to form organs
specific patterns of cell division or programmed cell death

22. Limb development eg. signals from apical ectodermal ridge  outgrowth
core of mesoderm transforms to cartilage
inward migration of muscle cells from somites
apoptosis (cell death) between developing digits in paddle
KLES

24. specialised cell types
What is a stem cell?
Examples of
differentiated or
specialised cell types
Self-renewal
Specialisation
Characteristics of stem cells
unspecialised
capable of self-renewal
can become differentiated
or specialised cell types

25. Potency and stem cell types
TOTIPOTENT
Fertilized egg
Whole organism
PLURIPOTENT
Blastocyst
All cell types
of embryo
Inner cell mass cells
Umbilical cord
blood
stem cells
MULTIPOTENT
Blood, muscle,
Bone, cartilage
Somatic tissue
stem cells
(or adult stem cells)
MULITPOTENT
Brain
Cornea
Bone Marrow
Gut
Skin
Liver
A glossary for stem cell biology
Smith Nature 441 : 1060

26. applications for stem cell technologies

27. What do I expect you to learn from this lecture?
process of spermatogenesis and oogenesis
broad features of developmental processes
cleavage
blastulation
gastrulation
neurulation
derivatives of germ layers
stem cells
definition
potency
applications