Chapter 1-

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Chapter 1- The anatomical tradition

• ______________- progressive change in
  multicellular organisms
• ___________- study of animal development
• _________________ development embryology

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Big questions

• What dictates _________________?
• How can cells form ordered ___________?
• How are _________ cells set apart?
• How do cells know when to stop _____________?
• How do cells know where to ___________?

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Historical settingPre-1800s - Two theories

• 1. ___________ theory-
• All organs prefigured, but very small
• Backed by science, religion, philosophy

• 2. ______________
• All organs made de novo (from scratch)

• Early 1800s- staining techniques/microscopy
• disprove preformation theory-
• The birth of _______________
• Late 1800s- _______ (instead of goo) theory
• recognized

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Fate mapping- the mapping of cell lineage
Strange terminology
5

• _____________- Organisms with three primary germ
  layers
• _______________- lack a true mesoderm
• Hydra, jellyfish, sponges
• ________________- Cells receiving cues from other
  cells

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Four Principles-Von Baers laws

• 1. ___________features appear prior to
  ______________ ones
• All vertebrates have gill arches, notochords,
  primitive kidneys
• 2. Less general characters are developed from
  _______ general (i.e. specialized from
  non-specialized)
• Scales vs. feathers
• Legs vs. wings
• Nails vs. claws
• 3. An embryo does not pass through the
  ___________________ of other, lower creatures
• 4. Thus, the early embryo of a higher animal in
  never like a lower animal, but only like its
  ___________________.
• Humans never look like ____________

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Fate mapping

• Major layers-
• _____________-
• Outer embryo layer
• Skin
• Nerves
• ______________-
• Inner embryo layer
• Digestive tract
• Respiratory system
• _____________-
• Middle layer
• Blood
• Heart
• Kidney
• Gonads
• Bones
• Connective tissue
• Muscle

Commit these to memory
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Homologous vs Analogous
Human arm

• ________________- Similarity arising from a
  common ancestral structure
• e.g. bird wing and human arm
• _______________- Similar function, but not
  common ancestor
• e.g. bird wing and insect wing

Seal limb
Bird wing

• Bat wing

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Teratology

• Environmental agents causing disruption of
  development -called ________________
• Example- __________________ (1961)

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Chapter 2- Life cycles

• All animals follow similar life cycle
• __________________- mixing of genetic material
  between sperm and egg
• ___________________- events between fertilization
  and hatching (or birth)

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General Animal Development
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The Frog Life cycle
Animal pole
100s of fertilized eggs
Unfertilized egg (Stained)
Vegetal pole
Note Cells get smaller, but egg ___________
remains the same!
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The Frog Life cycle- gastrulation through neurula
1. _______________________________ forms at
belly
2. Dorsal blastopore lip becomes the ____________
(a circle) 3. Ectoderm cells encase 4. Mesoderm
cells migrate inside along blastopore edges
5. Neural folds and groove appear
Fig. 2.3
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The Frog Life cycle- metamorphosis
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A unicellular protistThe goo theory can work!
What happens if we swap nuclei??
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Sexual reproduction

• Sex and reproduction are two distinct processes
• Sex- mixing of genetic material from two
  individuals
• Reproduction- creation of new individuals

• Bacteria, amoeba- Reproduction without sex
• _________________- Sex without reproduction

Swap micronuclei then separate

• ________________- Sex with reproduction

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Chlamydomonas (A eukaryote)
Chromosome mixing
Fig. 2.8
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• Unicellular eukaryotes have basic developmental
• processes observed in higher organisms
• -
• Mitosis and meiosis is accomplished
• Sexual reproduction
• Chromosomal structure is stable and similar

But, multicellular organisms are a whole new ball
game
These require cell-cell communication and
distinct cell functions _________________________
________
Example Volvox
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Example Volvox
Principle 1 One cell ______________ into 4-64
cells
Single cell
Gonium
Chlamydomonas
Panadorina
2000 cells
Somatic cells (appear as dots)
Germ cells
Eudorina
Pleodorina
Volvox
Fig. 2.11
Principle 2 ___________________ of cell
types- somatic vs reproductive
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Multicellular aggregation to from a slug-
Dictystelium
Principle 3 _______ cells instructed to perform
specific functions
Travel to new food source
This cycle requires adhesion, _____________ and
______________.
A _______ is formed (2-4 mm )
Differentiate into _______ and spore case
Fig 2.17
gt10,000 cell _____________
Stalk dies, spores released
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(No Transcript)
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General Animal Development (From chapter 2)
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Chapter 3- Experimental Embryology

• Three major approaches
• External forces - ____________________
• Internal forces- ____________________
• Organ development (Morphogenesis)

1. External forces

• a. Sex determination
• Boellia- depends on where larva lands
• Alligator egg temperature - lt30C _________
  development

• b. Embryo ______________
• Butterflies- colors depend in season
• Frogs and UV light

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Chapter 3- Experimental Embryology
2. Internal forces

• A few definitions
• ____________________- development of specialized
  cell types
• ____________________- developmental fate is
  restricted
• Two stages-
• 1. ___________________- capable of becoming
  specific
• cell types, but decision is reversible
• 2. __________________- non-reversible cell fate
  decision

a. __________________specification- blastomere
cell fate is determined at blastula stage (e.g.
isolated blastomere will become same type if
removed from blastula)
Most ________________ do this
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Chapter 3- Experimental Embryology
2. Internal forces (continued)
b. ______________ specification- cell fate is
determined on where a cell finds itself (e.g.
isolated blastomere will become what surrounding
cells dictate)
Transplant cells
All ___________ do this
Cell fate dictated by location
c. Note- insects display __________
Specification- cell fate is determined in egg
cytoplasm
Removed cells are compensated
Fig. 3.11
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Chapter 3- Experimental Embryology
2. Internal forces (continued)
More definitions- __________- soluble molecule
that instructs cells to differentiate Concentratio
n ___________- A morphogen at different
concentrations depending on location of cell
Example of concentration gradient- the flatworm
(Hydra)
The French flag analogy to understand gradients
It grows back!
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2. Internal forces (continued)
A lot makes blue
French Flag Analogy
A modest amount makes white
A little makes red
Transplanted tissue retain its _____________,
but differentiates according to new
_______________
Fig. 3.19
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2. Internal forces (continued)
An example of a concentration gradient- Activin
levels dictate cell fate in Xenopus
Activin levels
Fig. 3.20
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A _________________ field- a group of cells whose
position and fate are specified with respect to
the same set of boundaries.
2. Internal forces (continued)

• The general fate of a cell group (e.g. tissue) is
  determined,
• but individual cells within that tissue can
  respond to
• new positional cues

Example- a _______ field -Transplantation of
cells specified for limb development results in
limb formation in new place -But nearby cells
will form a limb
Nematode infection disrupts normal limb field
Fig. 3.22
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Morphogenesis is the bigger question of how cells
within a given organ are in a precise place and
have a precise function.
3. Morphogensis

1. How are _________formed from populations of
   cells?
2. How are __________ constructed from tissues?
3. How do organs form in particular ____________,
   and how do migrating cells reach their
   destinations?
4. How do organs and their cells grow, and how is
   growth ____________________ throughout
   development?
5. How do organs achieve ____________? Compare leg
   and finger cross-sections- the same yet
   different.

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Observations- Mix cells from different cell types
in a culture dish, they migrate to pre-instructed
location.
3. Morphogensis (continued)
Mesoderm endoderm epidermis
Mesoderm epidermis
Mesoderm endoderm
How do the cells know where to go?
One model- The ____________ model Malcolm
Steinberg 1964
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Surface tension
3. Morphogensis (continued)
The _____________ model
20.1
Cells interact so as to form an aggregate with
the smallest _________________free energy
12.6
In other words, those with stronger _________
properties move to the _________ of a cell mass
8.5
4.6

• Adhesion is dictated by
• Number of cell adhesion molecules
• Type of cell adhesion molecules

1.6
Fig. 3.30
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3. Morphogensis (continued)

• _____________ Calcium-dependent adhesion
  proteins
• - a major class of proteins that mediate cell
  adhesion
• Establish intercellular connections
• Required for _____________ segregation
• Required for organization of animal formation

Cadherin
Cadherins bind to __________in cells, which
bind to actin cytoskeleton
Catenins
Fig. 3.31
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3. Morphogensis (continued)
Cadherin types
___-cadherin- in all mammalian embryos, then
restricted in epithial tissues of embryos and
adults
___-cadherin- primarily in placenta
___-cadherin- in mesoderm and developing central
nervous system
____-cadherin-required for blastomere adhesion
Cadherins are responsible for cell sorting
Cells with different cadherin _____sort
Cells with different ___________ sort
Fig. 3.31