L4 Flashcards
What is the structure that is implanted in the uterus
Blastocyst
The bilaminar a germ disk is composed of
ICM that is differentiated into epiblast and hypoblast
Fertilization occurs in___ while implantation is in___
The ampulla of the uterine tubes
The body of the uterus
Cuboidal cells
Hypoblast
Describe the cytotrophoblast
Inner layer of mononucleated cells
Describe syncytiotrophoblast
Outer layer multinucleated zone without distinct cell boundaries
Describe the hypoblast 
Cuboidal cells adjacent to the blastocyst cavity
Describe epiblast
Columnar cells adjacent to the amniotic cavity
How is the Amnioblast formed
Embryoblast pulls away from the trophoblast forming a hollow Amniotic Cavity. Epiblast cells adjacent to the cytotrophoblast are called amnioblasts
-secretes hCG
syncytiotrophoblast
The extraembryonic mesoderm splits into 2 layers
Somatic splanchnic 
Extraembryonic mesoderm is formed from
Hypoblast
What are the events of the second week of development
• The trophoblast differentiates into 2 layers
• The embryoblast forms 2 layers
• The extraembryonic mesoderm splits into 2 layers
• Two cavities form
• bilaminar disk
Mention the events of the third week of development
Formation of the primitive streak
Appearance of primitive node
Migration of the epiblast cells toward the primitive streak
Formation of the 3 germ layers
Trilaminar disk
GASTRULATION GASTRULATION GASTRULATION
The primitive node know it appears at the__- region
Cephalic end of the primitive streak
The endoderm and mesoderm form from the
MIGRATION of the epiblast 
The ectoderm is formed from the_
REMAINING cells of the epiblast
Signals a lot of transcription factors to indicate how gastrulation will occur
Primitive node
Where is the primitive streak located
Caudomedial
Indicates early signs of gastrulation
Primitive streak
Interpret: all the body develops from epiblast
All the body develops from the MIGRATING epiblasts because they form the three germ layers
Gives rise to the umbilical cord
Extraembryonic mesoderm from hypoblast
Gives rise to the placenta
Syn. Trophoblast
Will give rise to the notochord
Prenotochordal cells
What is the job of the notochord
Established by the axis
signaling molecules
It was eventually disintegrate and the remnants will be in the vertebral disc
What is the function of cavities
Nourish the embryo
Where does the primitive node it appears
Cephalic end OF THE PRIMITIVE STREAK
The primitive streak appears on the ___
what is the primitive node __
Caudal end
cephalic end
Organizes the migration of epiblast sense to form three germ layers
Primitive node
Ensures which transcription factors or genes will be expressed at which time
Primitive node
Which cells give rise to the notochord
Mesoderm
How do the notochord forms from the mesoderm
They attached to the endoderm forming a notochord plate then they detach from it
What are the two types of mesoderm
Intraembryonic
extraembryonic
The intraembryonic mesoderm differentiates into
Paraxial lateral intermediate
Gives rise to somites
Mesoderm > intraembryonic > paraxial 
Development is(direction)
Cephalocaudal
Left to right
Ventral to dorsal
Which side is established first R or L?
Left
Establishment of the body axes is in which week
2 and 3
Which genes regulate head development
HESX1
LIM1
OTX2
What is the location of the cells that regulate head development
Anterior, cranial and, AVE(endoderm)
OTX2 LIM1 AND HESX1 results in (2)
Anteroposterior axis
Head formation
what occurs during gastrulation
Ventralization and dorsalization
What genes are responsible for ventralization
BMP4 FGF
BMP4 FGF are secreted through
Bilaminar disk
BMP4 FGF result in
Ventralization of mesoderm—> intermediate and lateral
Which gene transcription factor is responsible for dorsalization
Goosecoid
Goosecoid is expressed in
Node
Goosecoid results in
Regulate chordin expression + noggin + follistatin = inhibits the activity of BMP4 =
dorsalize:
mesoderm —> notochord
Paraxial mesoderm —> head
Brachyury T gene results in
Inhibits BMP4 = dorsalize
Mesoderm —> notochord
Paraxial —> caudal 
Ventralization is related to what types of mesoderm
Lateral intermediate
Dorsalization is related to what types of mesoderm
Paraxial
—> head in goosecoid
—> caudal BT gene
Which GTF regulates caudal genesis
BT gene
Which GTF regulates crainal genesis
HESX1
LIM1
OTX2
GOOSECOIDS // PARAXIAL —> CRAINAL
Which GTF regulates dorsal genesis
BT gene
Goosecoids
Which GTF regulates ventral genesis
BMP4 FGH
FGF8 results in
Establish the nodal protein
Nodal proteins is a part of which superfamily
TGF-B
Nodal protein accumulates on the
Left side
What induces nodal, lefty1 and lefty 2 expression
FGF8 under the influence of 5HT
And
Brachyury T gene
Regulates PITX2
Nodal and lefty 2
PITX2 results in
Inc left side expression
on what side are Lefty 1 and 2
1– ventral, left side of the neural plate
2- lateral plate mesoderm
SHH results in
Mid line barrier
Inc left side genes on the right
Are expressed in the NODE
Goosecoids
FGF8
Nodal
Chordin
Follistatin
Noggin
Expressed in the notochord
SHH
BT gene
Epiblast cells adjacent to the cytotrophoblast are called
amnioblasts
As the neural plate starts to form, neurotransmitter serotonin (5HT) increases in concentration on the left side why?
Because MAO metabolizes 5HT on the right
Expression of the transcription factor Snailresults in
regulate downstream genes important for establishing right-sidedness
establish right-sidedness
Snail
The Extraembryonic mesoderm splits into two layers that are located between
Cytotrophoblast and exocoelomic membrane
Dorsalizing the mesoderm is required for the development of
Notochord
BT gene : meso —> notocord
Goosecoid: meso —> notocord
Which protein is required for mesoderm to Differentiate into three segments
BMP4
What guides migration of epiblast from the primitive pit
TGF, nodal
Provides cellular supply for the formation of three germ layers
Epiblast
Causes mesoderm to differentiate into an embryo
FGF8
From where do the epiblast sells migrate to form the Notochordal process
Primitive node
Insufficient development of which embryonic structure leads to caudal dysgenesis
Mesoderm
Which abnormality is associated with old age 
Neural tube defects
Gastrulation is initiated by
 primitive streak
