Chapter 11-Reporting Flashcards
is a process where an active neuron can suppress synapse formation by other neurons on the same target
gastrulation
It extends beneath the neural tube,
forming bands of mesodermal cells
notochord
is specified by the Noggin protein’s antagonism of BMP signaling
paraxial mesoderm
forms the vertebrate and rib cartilage
sclerotome
form the musculature back, rib cage and ventral body dome
myotome
Contains skeletal
muscle progenitor cells and cells that
generate the dermis of the back
dermomyotome
- Arises from the most dorsal
sclerotome that generates tendons
syndetome
Forms from the internal
cells of the sclerotome. Forms vertebral
joins, intervertebral disc, and
proximal portion of the ribs
arthronome
what are the components of somatogenesis?
periodicity, fissure formation, epithelialization, specification, and differentiation
somite formation begins in the anterior trunk
periodicity
somites are separated
fissure formation
somites are shaped by the presomitic mesoderm
epithelialization
somites are shaped by the mesoderm’s structure
specification
somites differentiate into different parts
differentiation
involves the peeling away of
surface ectoderm, revealing well-formed somite and paraxial mesoderm
somite formation
This is rounding into a
somitomere, and neural crest cells migrate
ventrally from the neural tube roof.
paraxial mesoderm
- In chick embryos, a new somite is formed every _______________, while in mouse embryos, this time
frame is more variable
90 minutes
the formation of somites during
the development of an embryo.
somitogenesis
are precursors to many structures in
our bodies, including the vertebrae and
skeletal muscles.
somites
this is a key player in
somitogenesis. It helps determine where and
when somites form, acting like a master
conductor orchestrating the formation of these structures.
Notch signaling pathway
Mammals possess four
different notch receptors, referred to as
NOTCH1, NOTCH2, NOTCH3, and
NOTCH4¹.
notch receptor
The expression pattern of a gene called
_________ wave, rising and falling.
hairyl
- This is another important gene
in this process. - Activated by Notch, its protein product
initiates reactions that suppress Notch
activity.
Mesp2/c-Mesol
In the rostral, or anterior half, it induces a
gene called ___________
Eph A4
Through these processes, the somite
boundary is determined, and the somite is
given anterior/posterior polarity at the
same time.
somite boundary and polarity
- this is not a time-telling
clock, but one that regulates the
development of an organism. - is a network of
genes whose expression oscillates
synchronously and thereby regulates the
timing of developmental events.
segmentation clock
a protein that plays a critical role in
cell growth, differentiation, and
migration.
FgfS or Fibroblast Growth Factor
is a complex network
of proteins best known for their roles
in embryogenesis and cancer.
Wnt signaling
- is a highly conserved
pathway that regulates cell-cell
interactions crucial to multiple cell
differentiation processes. - can inhibit its own
activity in a negative feedback loop,
maintaining a delicate balance.
notch clock
This is a highly conserved cell signaling
system present in most animals. It
coordinates cellular differentiation
during development and homeostasis
in numerous organs and tissues across
metazoans1
notch signaling pathway
This mechanism involves an
oscillating signal (the clock) provided
by cascading genetic networks, while
a gradient of fibroblast growth factor
(FGF) provides the somite boundaries
(the wave).
clock and wavefront mechanism
a theoretical framework that describes
the segmentation clock as a network of
coupled oscillations in the Notch, Wnt,
and FGF signaling pathways. This
model suggests that the formation of
somites in the course of vertebrate
segmentation is governed by an
oscillator known as the segmentation
clock.
Goldbeter and Pourquie model
are blocks of mesoderm that
are located on either side of the neural
tube in the developing vertebrate
embryo.
somites
Somites give rise to important
structures such as the ____________ and _____
vertebrae, ribs
Snake embryos, for instance, can
have ____________ of somites.
hundreds
is a crucial process
in embryonic development, leading to
the segmentation of the body plan.
somite formation
Ectodermal signals cause the
peripheral somitic cells to
undergo this transition by
lowering the levels of a protein
called ______________
Cdc42
o The receptor tyrosine kinase
__________ and its ligand, __________,
play a crucial role in somite
development
EphA4, ephrin B2
The epithelialization of each
somite is stabilized by the
synthesis of the extracellular
matrix protein ___________ and
the adhesion protein ________________
fibronectin, N-cadherin.
this which will eventually form the
somites, is determined by its position
along the anterior-posterior axis
before somitogenesis, the process of
somite formation
segmental plate mesoderm
The regulation of the ______________ by the
segmentation clock allows
coordination between the formation
and the specification of the new
segments.
Hox genes
blocks of cells derived from the separation
of paraxial mesoderm which are highly important in
the organization of segmental parts of vertebrate
embryos.
somite
what are the somite-derived structures?
- Cartilage of the vertebrates and ribs.
- Muscles of the rib cage, limbs, abdominal
wall, back, and tongue. - Tendons (muscles to bones connection).
- Dermis of the dorsal skin.
- Vascular cells (contributes to the formation
of the aorta and intervertebral blood vessels). - Cellular sheaths, or meninges, of the spinal
cord (protects the central nervous system).
what are the three major compartments of mature somite?
schlerotome, dermomyotome, and myotome
- is a portion of the somite that
gives rise to mesenchymal cells which
become the cartilage cells (vertebrae and
major part of each ribs
schlerotome
the remaining epithelial
portion of the somite
dermomyotome
- central portion of the
dermomyotome.
⮚ forms the back dermis and other
derivatives.
⮚ give rises to a third population of
muscle cells.
dermatome
- the two lateral portions of the
epithelium (dorsomedial and ventrolateral
lips closest and farthest from the neural tube).
● forms the muscle cells
Myotome
The muscle precursor in the lateral
myotome will move beneath the
dermomyotome producing the _____________
which are the lower layer of muscle
precursor cells.
myoblasts
Myoblast closest to the neural tube forms
________________ including the intercostal
musculature between the ribs, and the deep
muscles of the back while the myoblast
farthest from the neural tube produces
__________________of the body wall, limbs, and
tongue.
primaxial muscle, abaxial muscles
boundary between the primaxial and abaxial muscles.
● between the somite-derived and lateral plate derived dermis
lateral somitic frontier
holds the daughter cells
until downregulated letting the
daughter cells to move in separate
ways.
N-cadherin
undifferentiated muscle
precursor cells delaminated from the
epithelial plate joining the primary
myotome that proliferate rapidly.
myoblast cell
responsible for postnatal
muscle growth and muscle repair.
satellite cell
- source of Sonic hedgehog and Noggin.
⮚ Critical for sclerotome formation
⮚ Produces compounds directing
the migration of sclerotome cells
to the center of the embryo
forming the vertebrae.
⮚ Degenerates by apoptosis
notochord
source of Wnts and
BMPs
neural tube and surface epithelium
induced schlerotome cells by paracrine factors
transcription factor Pax 1 an I-mf
EMT and cell
differentiation into cartilage
transcription factor Pax 1
inhibitor of myogenic (muscle forming) family of transcription factors
I-mf
– generates the meninges of the spinal cord, as well as, the blood vessels
medial mesenchymal cells
– the central region of the somites
composed of mesenchymal cells which become the vertebral joints, intervertebral discs, and rib portions
closest to the vertebrae
arthrotome
generates the muscle
precursor and the dermal cells constituting the
connective tissue layer of the dorsal skin
central dermomyotome
a sharp demarcation
between the somite- and lateral plate-derived dermis
lateral somitic factor
FACTORS REGULATING THE EMT OF THE
CENTRAL DERMOMYOTOME
neurotrophin-3 and Wnt1
prevents the conversion of the epithelial dermatome into loose dermal mesenchyme once activities are blocked by antibodies.
neurotrophin-3
promotes the differentiation of
the dorsally migrating central
dermomyotome cells into dermis.
Wnt1
plays a key role in energy utilization by
burning fats.
brown adipose cell (brown fats)
brown fat cells have the
same somitic precursor
with skeletal muscles
BHLH proteins
vital for myoblast conversion into
brown fat cells.
transcription factor PRDM16
from the medial portion of the
somite induced by the factors from the neural tube.
primaxial myoblast
from the lateral edge of the somite
❖ specified by the Wnt proteins (epidermis)
and the signals (lateral plate mesoderm)
abaxial myoblast
influence the myoblasts
migration away from the dorsal region
delaying the differentiation until they are
more ventrally located.
scatter factor
INHIBITORY SIGNALS – inhibiting the BMP4
sonic hedgehog and noggin
CONDITIONS NEEDED TO PRODUCE MUSCLE
PRECURSORS
- Presence of the Wnt signals
- Absence of the BMPs
⮚ In the paraxial mesoderm
o Synthesis and secretion of the
BMP inhibitor Noggin
o Promotion of the myoblast
formation
⮚ When removed
o Decreases the skeletal
musculature
o Weak ventral body wall
o Herniated heart and
abdominal organs
epiblast cells
MyoD and MyfS belong to a family of
transcription factors called the __________________________ proteins (sometimes also
referred to as myogenic regulatory factors,
or MRFs)
bHLH (basic helix-loop-helix)
It can activate other genes whose
products act as cofactors for MyoDs binding
to a later group of enhancers
MyoD
One type of putative stem cell, the________________, is found within the basal lamina of
mature myofibers. It respond to
injury or exercise by proliferating into
myogenic cells that fuse and form new
muscle fibers; these cells may be stern cells
with the capacity to generate daughter cells
for renewal or differentiation.
satellite cells
THREE DISTINCT LINEAGES THAT GENERATES THE SKELETON
somite, lateral plate mesoderm, cranial neural crest
Generate the axial ( Vertebral
Skeleton)
somite
Generates the limb skeleton
lateral plate mesoderm
Gives rise to the pharyngeal arch and craniofacial bones and cartilages
cranial neural crest
Two major modes of bone formation
intramembranous ossification and endochondral ossification
Direct conversion of mesenchymal tissue into bone. This process occurs primarily in the bones of the skull. In other cases, the mesenchymal cells differentiate into cartilage, and this cartilage is later replaced by bone.
intramembranous ossification
Is the process by which the embryonic
cartilaginous model of most bones contributes to longitudinal growth and is gradually replaced by bone.
endochondral ossification
Five stages of endochondral ossification
- Stage 1: Mesenchymal cells commit to becoming cartilage
cells. - Stage 2: Committed mesenchyme cells condense into compact nodules and differentiate into
chondrocytes or cartilage cells - Stage 3: Chondrocytes proliferate rapidity to form the cartilage model for the bone.
- Stage 4: The chondrocytes stop dividing and increase their volume dramatically, becoming hypertrophic chondrocytes
- Stage5: The blood vessels induced by VEGF invade the cartilage model
the first functional intra-embryonic
blood vessels, arise as two separate bilateral
vessels in the trunk and undergo lateral-to-medial translocation, eventually fusing into a single large vessel at the midline.
dorsal aortae
two cell layers of dorsal aorta
endothelial cell and smooth muscle cells
is derived from the ectoderm and
mesoderm. Progenitor cells of these originate from the ventral and lateral ectodermal areas. In animal models, in the crania and limb regions, it is formed in the absence of the muscle.
tendon
The most dorsal part of the sclerotome will become the fourth compartment of the somite, the ____________
syndetome
generates the urogenital
system such kidneys, gonads, and their respective duct systems.
intermediate mesoderm
- Functional unit of kidney consisting more than 10,000 cells and at least 12 different cell types
- derived from Greek word- nephros meaning kidney
nephron
what are the function of nephron?
filtration, reabsorption and secretion.
Three Major Forms of Mammalian Kidney Developmental Progress
pronephros, mesonephros, and metanephros
arises in the intermediate mesoderm ventrolateral to anterior somite.
Cells of this duct leads to formation of pronephros, the tubules of initial kidney or the pronephric tubules, due to the
migration of cells caudally, and the anterior region of the duct induces the adjacent mesenchyme forming this.
pronephros
First epithelial tubule to differentiate
from intermediate mesoderm which crucial for all further urogenital development
wolffian duct
arise as pronephric tubules degenerate, and middle portion of nephric duct induces new set of kidney tubules.
mesonephros
In humans, about ___ mesonephric tubules form, beginning around day 25.
30
A permanent kidney of amniotes
which originates through complex set of interaction between epithelial and mesenchymal components of
the intermediate mesoderm.
metanephros
Steps in Early Stage of Kidney Development
- The kidney forming METANEPHRIC/
METANEPHROGENIC MESENCHYME
becomes committed in the posterior regions of intermediate mesoderm - The ureteric buds, which are epithelial branches eventually grow out from the nephric duct.
- Entering metanephric mesenchyme
- Inducing mesenchymal tissue to condense around them and differentiate into the nephrons of the mammalian kidney
- As the mesenchyme begins to differentiate, it tells the ureteric bid to branch and grow.
plays several roles in the formation of the mouse kidney. (Early in development it is needed for converting the intermediate mesenchyme into the nephric duct, and later it is required for the formation
of the ureteric bud and the nephrons that form from mesonephric and metanephric mesenchyme)
Lim1
(determine the anterior-posterior body axis) makes cells competent to express Lim and make a kidney
hox
secreted by the neural tube. (This competence to respond to activin is established by the transcription factor Hoxb4, which is
not expressed in the anterior most region of the intermediate mesoderm)
TGF- β superfamily paracrine factor
-two distinct progenitor cell populations derived from the intermediate mesenchyme
ureteric bud and metanephric mesenchyme
gives rise to all of the cell
types that compose the mature collecting
ducts and the ureter,
ureteric bud
gives rise to all of the cell types that compose the mature nephron, as well as to some vascular and stromal derivatives.
metanephric mesenchyme
this occurs when the two interacting tissues are both inducers and
are competent to respond to each other signals
mechanism of reciprocal induction
what are the mechanism of reciprocal induction?
- STEP 1. Formation of Metanephric Mesenchyme and the Ureteric Bud
- STEP 2. The Metanephric Mesenchyme Induces Outgrowth of the Ureteric bud.
- STEP 3. The Ureteric Bud Prevents Mesenchymal Apoptosis
- STEP 4. The Mesenchyme Induces the Branching of the Ureteric Acid
- STEP 5. Wnt Signals Convert the Aggregated
Mesenchyme Cells into a Nephron - STEP 6. Inserting the Ureter into the Bladder
It does not only induces the initial ureteric bud from the nephric duct but can also induce secondary buds from the ureteric bud once the bud enters the mesenchyme GDNF also induces Wnt 11 synthesis in the responsive cells at the tip of bud
Glial-derived neurotrophic factor (GDNF)
critical for transforming the
metanephric mesenchyme cells into tubular
epithelium. These paracrine signals induce yet
another Wnt in the mesenchyme
Wnt9b and Wnt6
act as autocrine manner to complete the
transition from mesenchymal mass to epithelium
Wnt4
This is critical for different gene
expression along the length of the new epithelium
Combination of signaling factors
a condition where one or both kidneys become stretched and swollen as the result of a build-up of urine inside them
hydronephrosis
made into a watertight connecting duct by the
condensation of mesenchymal cells around it.
ureter
portion where bladder develops
which will become the waste receptacle for
both the intestine and the kidney
cloaca
