Transcript MESODERM

The most complex problem
How to get from here
The most complex problem
How to get from here to there
LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 47
Animal Development
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Figure 47.1
A human embryo at about 7 weeks after conception
shows development of distinctive features
1 mm
Development: cellular level
• Cell division
• Differentiation
– cells become specialized in structure & function
• Morphogenesis (organogenesis)
Development: cellular level
• Cell division
• Differentiation
– cells become specialized in structure & function
• if each kind of cell has the same genes,
how can they be so different?
– shutting off of genes = loss of totipotency
– Turning genes on based on chemical cues
• Morphogenesis (organogenesis)
Development: cellular level
• Cell division
• Differentiation
– cells become specialized in structure & function
• if each kind of cell has the same genes,
how can they be so different?
– shutting off of genes = loss of totipotency
– Turning genes on based on chemical cues
• Morphogenesis (organogenesis)
– “creation of form” = give organism shape
– basic body plan
• polarity
– one end is different than the other
• symmetry
– left & right side of body mirror each other
• asymmetry
– look at your hand…
Our model organisms
Developmental events
EMBRYONIC DEVELOPMENT
Sperm
Zygote
Adult
frog
Egg
Metamorphosis
Blastula
Larval
stages
Gastrula
Tail-bud
embryo
Fertilization in sea urchins: fast block and slow
block to polyspermy
Basal body
(centriole)
Sperm
head
Acrosome
Jelly coat
Sperm-binding
receptors
Vitelline layer
Egg plasma membrane
Figure 47.3-2
Basal body
(centriole)
Sperm
head
Acrosome
Jelly coat
Sperm-binding
receptors
Hydrolytic enzymes
Vitelline layer
Egg plasma membrane
Figure 47.3-3
Sperm
nucleus
Basal body
(centriole)
Sperm
head
Acrosome
Jelly coat
Sperm-binding
receptors
Acrosomal
process
Actin
filament
Hydrolytic enzymes
Vitelline layer
Egg plasma membrane
Figure 47.3-4
Sperm
plasma
membrane
Sperm
nucleus
Basal body
(centriole)
Sperm
head
Acrosome
Jelly coat
Sperm-binding
receptors
Acrosomal
process
Actin
filament
Fused
plasma
membranes
Hydrolytic enzymes
Vitelline layer
Egg plasma membrane
Figure 47.3-5
Sperm
plasma
membrane
Sperm
nucleus
Basal body
(centriole)
Sperm
head
Acrosome
Jelly coat
Sperm-binding
receptors
Fertilization
envelope
Acrosomal
process
Actin
filament
Cortical
Fused
granule
plasma
membranes
Hydrolytic enzymes
Perivitelline
space
Vitelline layer
Egg plasma membrane
EGG CYTOPLASM
EXPERIMENT
10 sec after
fertilization
Slow block
RESULTS
to
polysperm
y: Change
in Ca++ in
the egg
makes f.e. 1 sec before
fertilization
25 sec
35 sec
1 min
10 sec after
fertilization
20 sec
30 sec
CONCLUSION
Point of sperm
nucleus
entry
Spreading
wave of Ca2
Fertilization
envelope
500 m
500 m
Egg Activation
• The rise in Ca2+ in the cytosol increases the rates
of cellular respiration and protein synthesis by the
egg cell
• With these rapid changes in metabolism, the egg
is said to be activated
• The proteins and mRNAs needed for activation
are already present in the egg
• The sperm nucleus merges with the egg nucleus
and cell division begins
© 2011 Pearson Education, Inc.
• When the sperm binds a receptor in the zona pellucida, it triggers a
slow block to polyspermy (no fast block to polyspermy has been
identified in mammals)
Zona pellucida
Follicle cell
Sperm
basal body
Sperm
nucleus
Cortical
granules
CLEAVAGE
•Fertilization is followed by cleavage, a period of rapid cell
division without growth
•Cleavage partitions the cytoplasm of one large cell into many
smaller cells called blastomeres
•The blastula is a ball of cells with a fluid-filled cavity called a
blastocoel
50 m
(a) Fertilized egg
(b) Four-cell stage (c) Early blastula
(d) Later blastula
Cleavage in a frog embryo
Zygote
2-cell
stage
forming
Gray crescent
0.25 mm
8-cell stage (viewed
from the animal pole)
4-cell
stage
forming
8-cell
stage
Animal
pole
0.25 mm
Blastula (at least 128 cells)
Vegetal pole
Blastula
(cross
section)
Blastocoel
Concept 47.2: Morphogenesis in animals
involves specific changes in cell shape,
position, and survival
• Morphogenesis, the process by which cells
occupy their appropriate locations, involves
– Gastrulation, the movement of cells from the
blastula surface to the interior of the embryo
– Organogenesis, the formation of organs
© 2011 Pearson Education, Inc.
Figure 47.8
ECTODERM (outer layer of embryo)
• Epidermis of skin and its derivatives (including sweat glands,
hair follicles)
• Nervous and sensory systems
• Pituitary gland, adrenal medulla
• Jaws and teeth
• Germ cells
MESODERM (middle layer of embryo)
• Skeletal and muscular systems
• Circulatory and lymphatic systems
• Excretory and reproductive systems (except germ cells)
• Dermis of skin
• Adrenal cortex
ENDODERM (inner layer of embryo)
• Epithelial lining of digestive tract and associated organs
(liver, pancreas)
• Epithelial lining of respiratory, excretory, and reproductive tracts
and ducts
• Thymus, thyroid, and parathyroid glands
Gastrulation in the sea urchin
Animal
pole
Blastocoel
Mesenchyme
cells
Vegetal plate
Vegetal
pole
Blastocoel
Filopodia
Mesenchyme
cells
Blastopore
Archenteron
50 m
Blastocoel
Ectoderm
Key
Future ectoderm
Future mesoderm
Future endoderm
Mouth
Mesenchyme
(mesoderm forms
future skeleton)
Archenteron
Blastopore
Digestive tube (endoderm)
Anus (from blastopore)
Gastrulation in frog embryo
1
CROSS SECTION
SURFACE VIEW
Animal pole
Blastocoel
Dorsal
lip of
blastopore
Early
Vegetal pole
gastrula
Blastopore
Blastocoel
shrinking
2
3
Blastocoel
remnant
Dorsal
lip of
blastopore
Archenteron
Ectoderm
Mesoderm
Endoderm
Key
Future ectoderm
Future mesoderm
Future endoderm
Late
gastrula
Blastopore
Blastopore
Yolk plug
Archenteron
Gastrulation in chicks
Fertilized egg
Primitive
streak
Embryo
Yolk
Primitive streak
Epiblast
Future
ectoderm
Blastocoel
Migrating
cells
(mesoderm)
Endoderm
Hypoblast
YOLK
1 Blastocyst reaches uterus.
Uterus
Embryonic
development
in humans
Endometrial epithelium
(uterine lining)
Inner cell mass
Trophoblast
Blastocoel
2 Blastocyst implants
(7 days after fertilization).
Expanding region of
trophoblast
Maternal
blood
vessel
Epiblast
Hypoblast
Trophoblast
3 Extraembryonic membranes
start to form (10–11 days),
and gastrulation begins
(13 days).
Expanding region of
trophoblast
Amniotic cavity
Epiblast
Hypoblast
Yolk sac (from hypoblast)
Extraembryonic mesoderm cells
(from epiblast)
Chorion (from trophoblast)
4 Gastrulation has produced a
three-layered embryo with
four extraembryonic
membranes.
Amnion
Chorion
Ectoderm
Mesoderm
Endoderm
Yolk sac
Extraembryonic mesoderm
Allantois
Figure 47.12a
Endometrial epithelium
(uterine lining)
Uterus
Inner cell mass
Trophoblast
Blastocoel
1 Blastocyst reaches uterus.
Figure 47.12b
Expanding region of
trophoblast
Maternal
blood
vessel
Epiblast
Hypoblast
Trophoblast
2 Blastocyst implants
(7 days after fertilization).
Figure 47.12c
Expanding region of
trophoblast
Amniotic cavity
Epiblast
Hypoblast
Yolk sac (from hypoblast)
Extraembryonic mesoderm
cells (from epiblast)
Chorion (from trophoblast)
3 Extraembryonic membranes
start to form (10–11 days),
and gastrulation begins
(13 days).
Figure 47.12d
Amnion
Chorion
Ectoderm
Mesoderm
Endoderm
Yolk sac
Extraembryonic mesoderm
Allantois
4 Gastrulation has produced a
three-layered embryo with
four extraembryonic
membranes.
Developmental Adaptations of Amniotes
•
The colonization of land by vertebrates was
made possible only after the evolution of
1. The shelled egg of birds and other reptiles as
well as monotremes (egg-laying mammals)
2. The uterus of marsupial and eutherian mammals
© 2011 Pearson Education, Inc.
• The four extraembryonic membranes that form
around the embryo in a reptile/bird:
–
–
–
–
The chorion functions in gas exchange
The amnion encloses the amniotic fluid
The yolk sac encloses the yolk
The allantois disposes of waste products and
contributes to gas exchange
© 2011 Pearson Education, Inc.
Neuralation in a frog embryo
Eye
Neural folds
Neural
fold
Tail bud
Neural plate
SEM
1 mm
Neural
fold
Somites
Neural tube
Neural
plate
Notochord
Neural
crest cells
1 mm
Neural
crest
cells
Coelom
Notochord
Somite
Ectoderm
Mesoderm
Endoderm
Neural
crest cells
Outer layer
of ectoderm
Archenteron
(a) Neural plate formation
Neural
tube
(b) Neural tube formation
Archenteron
(digestive
cavity)
(c) Somites
Organogenisis in a chick
Neural tube
Notochord
Eye
Forebrain
Somite
Coelom
Endoderm
Mesoderm
Ectoderm
Archenteron
Lateral
fold
Heart
Blood
vessels
Somites
Yolk stalk
These layers
form extraembryonic
membranes.
(a) Early organogenesis
Yolk sac
Neural
tube
YOLK
(b) Late organogenesis
Ectoderm
Morphogenesis
results
from cells
changing
shape
Figure 47.15-2
Ectoderm
Neural
plate
Microtubules
Figure 47.15-3
Ectoderm
Neural
plate
Microtubules
Actin
filaments
Figure 47.15-4
Ectoderm
Neural
plate
Microtubules
Actin
filaments
Figure 47.15-5
Ectoderm
Neural
plate
Microtubules
Actin
filaments
Neural tube
Elongation of tissue by convergent extension
Concept 47.3:
What determines how parts form;
and messing with those determining factors
• Determination is the term used to describe the
process by which a cell or group of cells becomes
committed to a particular fate
• Differentiation refers to the resulting
specialization in structure and function
– Can result from: oocyte composition, logal signals,
gravity
© 2011 Pearson Education, Inc.
Epidermis
Fate
mapping
Central
nervous
system
Notochord
Epidermis
Mesoderm
Endoderm
Blastula
Neural tube stage
(transverse section)
(a) Fate map of a frog embryo
64-cell embryos
Blastomeres
injected with dye
Larvae
(b) Cell lineage analysis in a tunicate
Time after fertilization (hours)
Figure 47.18
Zygote
0
First cell division
Nervous
system,
outer skin,
musculature
10
Musculature, gonads
Outer skin,
nervous system
Germ line
(future
gametes)
Musculature
Hatching
Intestine
Intestine
Anus
Mouth
Eggs
Vulva
POSTERIOR
ANTERIOR
1.2 mm
Determination of germ cell fate in C. elegans.
100 m
How does distribution of the gray crescent affect the developmental potential of the first two daughter cells?
EXPERIMENT
Control egg
(dorsal view)
Experimental egg
(side view)
1a Control
1b Experimental
group
group
Gray
crescent
Gray
crescent
Thread
2
RESULTS
Normal
Belly piece
Normal
Figure 47.7b
0.25 mm
Animal
pole
8-cell stage (viewed
from the animal pole)
Figure 47.7c
0.25 mm
Blastocoel
Blastula (at least 128 cells)
Can the dorsal lip of the blastopore induce cells in another part of the amphibian embryo to change
their developmental fate?
EXPERIMENT
Dorsal lip of
blastopore
Pigmented
gastrula
(donor embryo)
RESULTS
Primary embryo
Secondary
(induced) embryo
Nonpigmented
gastrula
(recipient embryo)
Primary structures:
Neural tube
Notochord
Secondary structures:
Notochord (pigmented cells)
Neural tube
(mostly nonpigmented cells)
Figure 47.24
Anterior
Limb bud
AER
ZPA
Posterior
Limb buds
50 m
2
Digits
Apical
ectodermal
ridge (AER)
Anterior
3
4
Ventral
Proximal
Distal
Dorsal
Posterior
(a) Organizer regions
(b) Wing of chick embryo
• One limb bud–regulating region is the apical
ectodermal ridge (AER)
• The AER is thickened ectoderm at the bud’s tip
• The second region is the zone of polarizing
activity (ZPA)
• The ZPA is mesodermal tissue under the
ectoderm where the posterior side of the bud is
attached to the body
© 2011 Pearson Education, Inc.
EXPERIMENT
Anterior
New
ZPA
Donor
limb
bud
Host
limb
bud
ZPA
Posterior
RESULTS
What happens when you
put ZPA on both sides of a
budding limb?
Could you make a human with pinkies
on both sides of their hands?
EXPERIMENT
Anterior
New
ZPA
What role does
the zone of
polarizing
activity (ZPA)
play in limb
pattern formation
in vertebrates?
Donor
limb
bud
Host
limb
bud
ZPA
Posterior
RESULTS
4
3
2
2
4
3
• Sonic hedgehog is an inductive signal for limb
development
• Hox genes also play roles during limb pattern
formation
© 2011 Pearson Education, Inc.
Homeotic genes
• Mutations to homeotic genes produce flies
with such strange traits as legs growing from
the head in place of antennae.
antennapedia
– structures characteristic of a particular
part of the flies
animal arise in wrong place
Homeobox DNA
• Master control
genes evolved
early
• Conserved for
hundreds of
millions of years
• Homologous
homeobox genes in
fruit flies &
vertebrates
– kept their
chromosomal
arrangement
Cilia and Cell Fate
• Ciliary function is essential for proper specification
of cell fate in the human embryo
• Motile cilia play roles in left-right specification
• Monocilia (nonmotile cilia) play roles in normal
kidney development
© 2011 Pearson Education, Inc.
Figure 47.26
Lungs
Heart
Liver
Spleen
Stomach
Large intestine
Normal location
of internal organs
Location in
situs inversus