Title: Chapter 1-
1Chapter 1- The anatomical tradition
- ______________- progressive change in
multicellular organisms - ___________- study of animal development
- _________________ development embryology
2Big 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 ___________?
3Historical 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
4Fate 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
6Four 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 ____________
7Fate 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
8Homologous 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
9Teratology
- Environmental agents causing disruption of
development -called ________________ - Example- __________________ (1961)
10Chapter 2- Life cycles
- All animals follow similar life cycle
- __________________- mixing of genetic material
between sperm and egg - ___________________- events between fertilization
and hatching (or birth)
11General Animal Development
12The Frog Life cycle
Animal pole
100s of fertilized eggs
Unfertilized egg (Stained)
Vegetal pole
Note Cells get smaller, but egg ___________
remains the same!
13The 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
14The Frog Life cycle- metamorphosis
15A unicellular protistThe goo theory can work!
What happens if we swap nuclei??
16Sexual 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
17Chlamydomonas (A eukaryote)
Chromosome mixing
Fig. 2.8
18- 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
19Example 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
20Multicellular 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
21(No Transcript)
22General Animal Development (From chapter 2)
23Chapter 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
24Chapter 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
25Chapter 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
26Chapter 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!
272. 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
282. Internal forces (continued)
An example of a concentration gradient- Activin
levels dictate cell fate in Xenopus
Activin levels
Fig. 3.20
29A _________________ 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
30Morphogenesis is the bigger question of how cells
within a given organ are in a precise place and
have a precise function.
3. Morphogensis
- How are _________formed from populations of
cells? - How are __________ constructed from tissues?
- How do organs form in particular ____________,
and how do migrating cells reach their
destinations? - How do organs and their cells grow, and how is
growth ____________________ throughout
development? - How do organs achieve ____________? Compare leg
and finger cross-sections- the same yet
different.
31Observations- 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
32Surface 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
333. 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
343. 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