1. Biology Sylvia S. Mader Michael Windelspecht
Chapter 42
Animal Development
and Aging
Lecture Outline
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2. Biology, 9th ed, Sylvia Mader
Fertilization
Chapter 44
Animal Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
microvilli of oocyte plasma membrane
2. Acrosomal enzymes
digest a portion of
zona pellucida.
tail
3. Sperm binds to and
fuses with oocyte
plasma membrane.
sperm
1. Sperm makes its
way through the
corona radiata.
corona radiata
4. Sperm nucleus enters
cytoplasm of oocyte.
5. Cortical granules
release enzymes;
zona pellucida
becomes fertilization
membrane.
plasma
membrane
nucleus
middle
piece
head
acrosome
fertilization membrane
6. Sperm and egg
pronuclei are enclosed
in a nuclear envelope.
cortical granule
sperm pronucleus
oocyte plasma membrane
zona pellucida
egg pronucleus
© David M. Phillips/Visuals Unlimited; (Chick, p. 779): © Photodisc/Getty Images

3. Early Developmental Stages
Biology, 9th ed, Sylvia Mader
Chapter 44
Early Developmental Stages
Animal Development
Development – all changes that occur during the life cycle
First stages of development, organism is called an embryo
After fertilization, the zygote undergoes cleavage
Cleavage is cell division without growth
Morula forms a blastula with a hollow blastocoel

4. Cleavage Note: Size is not increasing

5. Blastula

6. Biology, 9th ed, Sylvia Mader
Chapter 44
Tissue Development
Animal Development
Gastrulation – formation of a gastrula
Germ layer formation and differentiation
Blastopore
Pore created by the inward folding of cells
Eventually becomes the anus

7. Biology, 9th ed, Sylvia Mader
Chapter 44
Embryonic Germ Layers
Animal Development

8. Biology, 9th ed, Sylvia Mader
Chapter 44
Organ Development
Animal Development
Formation of organs
1st to develop
Neural tube
Notochord
Skeletal rod

9. Neurulation

10. Organogenesis of Chick Embryo Rudimentary organs have formed (56 hours)
Eye
Forebrain
Heart
Somites
Neural Tube

11. Extraembryonic Membranes
Biology, 9th ed, Sylvia Mader
Chapter 44
Extraembryonic Membranes
Animal Development
Chorion –Gas exchange
Amnion –Fluid filled
Allantois – collects nitrogenous wastes (umbilical cord)
Yolk sac – provides nourishment
Presence of embryonic membranes in humans demonstrates our evolutionary relationship to reptiles

12. Extraembryonic Membranes
Biology, 9th ed, Sylvia Mader
Chapter 44
Extraembryonic Membranes
Animal Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
embryo
allantois
amnion
yolk sac
chorion
Chick
embryo
chorion
amnion
allantois
umbilical
cord
yolk sac
fetal portion
of placenta
maternal portion
of placenta
Human

13. Biology, 9th ed, Sylvia Mader
Chapter 44
Placenta
Animal Development
Mammalian structure that functions in gas, nutrient, and waste exchange between embryonic &maternal cardiovascular systems.
Begins formation once the embryo is fully planted

14. Three Stages of Parturition
Biology, 9th ed, Sylvia Mader
Chapter 44
Three Stages of Parturition
Animal Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ruptured
amniotic
sac
a. First stage of birth: cervix dilates
placenta
b. Second stage of birth: baby emerges
placenta
uterus
umbilical
cord
c. Third stage of birth: expelling afterbirth

15. Stem Cells: Undifferentiated Cells

16. 42.2 Developmental Processes
Biology, 9th ed, Sylvia Mader
Chapter 44
42.2 Developmental Processes
Animal Development
Development requires:
Growth
Cellular Differentiation
Cells become specialized in structure and function
Morphogenesis
Produces the shape and form of the body
Includes pattern formation
Arrangement of tissues and organs within the body
Involves apoptosis

17. Morphogenesis & Changes in Cell Shape

18. Major Stages of Embryogenesis

19. Developmental Processes
Biology, 9th ed, Sylvia Mader
Chapter 44
Developmental Processes
Animal Development
Cellular Differentiation
The zygote is totipotent
Cellular Differentiation (continued)
Cytoplasmic Segregation
Maternal determinants are parceled out during mitosis
Cytoplasm of a frog’s egg is not uniform

20. Cytoplasmic Segregation
Biology, 9th ed, Sylvia Mader
Chapter 44
Cytoplasmic Segregation
Animal Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
maternal determinants
Cytoplasmic segregation

21. Biology, 9th ed, Sylvia Mader
Chapter 44
Induction
Animal Development
The ability of one embryonic tissue to influence the development of another tissue Molecular concentration gradients may act as chemical signals to induce germ layer differentiation Developmental path of cells is influenced by neighboring cells

22. Cytoplasmic Influence on Development
Biology, 9th ed, Sylvia Mader
Chapter 44
Cytoplasmic Influence on Development
Animal Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
animal pole
Dorsal
plane of
first division
gray
crescent
Anterior
site of
sperm
fusion
Posterior
Ventral
vegetal pole
Dorsal
Anterior V
entral
Posterior
a. Zygote of a frog is polar and has axes.
b. Each cell receives a part of the gray crescent
c. Only the cell on the left
receives the gray crescent

23. Determination & Differentiation

24. Pattern Formation in Drosophila
Biology, 9th ed, Sylvia Mader
Chapter 44
Pattern Formation in Drosophila
Animal Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a.
Hox-2
mouse
chromosomes
Hox-1
Hox-3
Hox-4
fly chromosome
mouse
embryo
fruit fly embryo b.
mouse
fruit fly
Courtesy E.B. Lewis

25. Apoptosis: programmed cell death

26. Developmental Processes
Biology, 9th ed, Sylvia Mader
Chapter 44
Developmental Processes
Animal Development
Homeotic Genes control pattern formation
Organization of differentiated cells into specific three-dimensional structures
In Drosophila, certain genes control whether a particular segment will bear antennae, legs, or wings
Homeotic genes all contain the same particular sequence of nucleotides, the homeobox, that encodes a 60-amino-acid sequence called a homeodomain

27. How does this happen?