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