Animal Development - Chapter 47 Flashcards
Classical embryology
description of development in model organisms
induction
one type of tissue influences the development of another tissue
Development Stages
Fertilization
Early Cleavages
Blastula (hollow ball of cells)
Gastrulation (forms the gastrula)
Organogenesis (formation of organs)
Ectoderm
epidermis, nervous system
Mesoderm
skeleton muscles
Endoderm
digestive, reporductive
Underlying mechanisms of organogenesis
Organosgenesis are localized changes
cell migration
cell signaling between different tissues
cell shape changes genrating new organs
Cell movement
reorganize cytoskeleton
microtubules and microfilaments (actin)
(cells crawl using the cytoskeleton fibers to extend (extension) and retract (convergence) extensions
Amniotes
reptiles
birds
mammals
all have a way of developing in “watery” environments
4 extraembryonic membranes of amniotes
evolved as adaptation to terrestrial envroniment
Amnion
Chorion
Allantosis
Yolk Sac
Amnion
protects embryo in a sac
Chorion
lines the inner surface of the shell (which is permeable to gases) and participates in exchange of O2 and Co between embryo and outside air
Allantosis
stores metabolic wastes (mostly uric acid) of the embryo and as it grows larger, also participates in gas exchange
Yolk Sac
contains yolk - the sole source of food until hatching
Placental mammal development
cleavage in oviduct produces blastocyst
Placenta
produces progesterone beginning in the 2nd trimester (as hCG declines and corpus luteum atrophies)
(no direct connection between maternal and fetal blood vessels)
Human fetal development
zygote -> embryo (>2cells) -> fetus (8 weeks)
positive feedback in labor
3 stages of labor
- dilation of cervix
- expulsion - delivery
- delivery of placenta
Teratogenesis
environment causes a developmental abnormality
description of development in model organisms
Classical embryology
one type of tissue influences the development of another tissue
induction
Fertilization
Early Cleavages
Blastula (hollow ball of cells)
Gastrulation (forms the gastrula)
Organogenesis (formation of organs)
Development Stages
epidermis, nervous system
Ectoderm
skeleton muscles
Mesoderm
digestive, reporductive
Endoderm
Organosgenesis are localized changes
cell migration
cell signaling between different tissues
cell shape changes genrating new organs
Underlying mechanisms of organogenesis
reorganize cytoskeleton
microtubules and microfilaments (actin)
(cells crawl using the cytoskeleton fibers to extend (extension) and retract (convergence) extensions
Cell movement
reptiles
birds
mammals
all have a way of developing in “watery” environments
Amniotes
evolved as adaptation to terrestrial envroniment
Amnion
Chorion
Allantosis
Yolk Sac
4 extraembryonic membranes of amniotes
protects embryo in a sac
Amnion
lines the inner surface of the shell (which is permeable to gases) and participates in exchange of O2 and Co between embryo and outside air
Chorion
stores metabolic wastes (mostly uric acid) of the embryo and as it grows larger, also participates in gas exchange
Allantosis
contains yolk - the sole source of food until hatching
Yolk Sac
cleavage in oviduct produces blastocyst
Placental mammal development
produces progesterone beginning in the 2nd trimester (as hCG declines and corpus luteum atrophies)
(no direct connection between maternal and fetal blood vessels)
Placenta
zygote -> embryo (>2cells) -> fetus (8 weeks)
positive feedback in labor
Human fetal development
- dilation of cervix
- expulsion - delivery
- delivery of placenta
3 stages of labor
environment causes a developmental abnormality
Teratogenesis
Acrosomal reaction
the acrosome releases hydrolytic enzymes that make a hole in the jelly coat of the egg. The acrosomal process forms.
This trigger changes the membrane potential of the egg because sodium ions diffuse into the egg and cause depolarization.
When does the cortical reaction in sea urchins occur?
within seconds of the sperm entering the egg.
Ion released from the ER and how it affects the cortical granules
Cortical Granules
calcium
it causes the cortical granules to fuse with the plasma membrane
this triggers the formation of a fertilzation membrane by lfting the vitelline layer away from the egg and hardents it into a fertilzation membrane
slow block to polyspermy
evidence that mRNA needed to produce enzymes involved in very early development are already in the egg before fertilization
even when the nucleus has been removed, artificial activaiton is still possible
Where in the egg’s meiotic cycle does fertilzation occur in humans? in sea urchins?
metaphase II (12-36 hours after sperm binding)
completed meiosis (90 minutes after sperm binding)
Cleavage
rapid cell divisions
no substantial growth
Vegetal pole
yolk most concentrated at this end
Meroblastic cleavage (bird)
holoblastic cleavage (frog and sea urchin)
so much yolk that the cleavage furrow does not entirely pass through
cleavage furrow passes entirely through the egg
Unique cleavage in insects like Drosophila
sperm and egg fuse within a yolk mass and multiple rounds of mitosis occurs without cytokinesis
Blastula
blastocoel
hollow ball of cells
fluid-filled cavity surrounded by the blastula
gastrula
gastrulation
germ layered embryo forms
reorganizing the blastula into the gastrula
archenteron
blastopore
tube formed from shallow depresson
open end of archenteron
yolk plug
formed from leftovers in creating the dorsal lip of the blastopore - vegetal pole
organogenesis
formation of organs
how germ layers form
epiblast cells migrate towards the midline of the blastoderm, detach, and move inward
notochord
rod that extends along the dorsal side of the chordate embryo
neural tube
runs along the anterior-posterior axis of the embryo, formed form the neural plate
somites
blocks formed froms cells migrating together.
along the length of the notochord
embryonic evidence for a segmented body plan in the chordates
cells arise by division
specializaiton of cells duirng development
differentiation
Bilateral symmetry
symmetry dorsal-ventral, anterior-posterior axes, and right-left
how is this basic body plan established early in development in non-mammalian species?
during oogenesis (animal-vegetal poles determine symmetry) animal pole is the point of sperm entry, cortical reaction at fertilization determines dorsal-ventral axis
basic body plan established early in mammals?
no polarity, might have to do with orientation
Developmental potential
range of structures that cells can give rise to
Totipotent
cell can develop into any structure of that animal
the acrosome releases hydrolytic enzymes that make a hole in the jelly coat of the egg. The acrosomal process forms.
This trigger changes the membrane potential of the egg because sodium ions diffuse into the egg and cause depolarization.
Acrosomal reaction
within seconds of the sperm entering the egg.
When does the cortical reaction in sea urchins occur?
calcium
it causes the cortical granules to fuse with the plasma membrane
this triggers the formation of a fertilzation membrane by lfting the vitelline layer away from the egg and hardents it into a fertilzation membrane
slow block to polyspermy
Ion released from the ER and how it affects the cortical granules
Cortical Granules
even when the nucleus has been removed, artificial activaiton is still possible
evidence that mRNA needed to produce enzymes involved in very early development are already in the egg before fertilization
metaphase II (12-36 hours after sperm binding)
completed meiosis (90 minutes after sperm binding)
Where in the egg’s meiotic cycle does fertilzation occur in humans? in sea urchins?
rapid cell divisions
no substantial growth
Cleavage
yolk most concentrated at this end
Vegetal pole
so much yolk that the cleavage furrow does not entirely pass through
cleavage furrow passes entirely through the egg
Meroblastic cleavage (bird)
holoblastic cleavage (frog and sea urchin)
sperm and egg fuse within a yolk mass and multiple rounds of mitosis occurs without cytokinesis
Unique cleavage in insects like Drosophila
hollow ball of cells
fluid-filled cavity surrounded by the blastula
Blastula
blastocoel
germ layered embryo forms
reorganizing the blastula into the gastrula
gastrula
gastrulation
tube formed from shallow depresson
open end of archenteron
archenteron
blastopore
formed from leftovers in creating the dorsal lip of the blastopore - vegetal pole
yolk plug
formation of organs
organogenesis
epiblast cells migrate towards the midline of the blastoderm, detach, and move inward
how germ layers form
rod that extends along the dorsal side of the chordate embryo
notochord
runs along the anterior-posterior axis of the embryo, formed form the neural plate
neural tube
blocks formed froms cells migrating together.
along the length of the notochord
somites
cells arise by division
embryonic evidence for a segmented body plan in the chordates
differentiation
specializaiton of cells duirng development
symmetry dorsal-ventral, anterior-posterior axes, and right-left
Bilateral symmetry
during oogenesis (animal-vegetal poles determine symmetry) animal pole is the point of sperm entry, cortical reaction at fertilization determines dorsal-ventral axis
how is this basic body plan established early in development in non-mammalian species?
no polarity, might have to do with orientation
basic body plan established early in mammals?
range of structures that cells can give rise to
Developmental potential
cell can develop into any structure of that animal
Totipotent
