Embryology II Flashcards
At this point in the picture, what happens to the cells on top of the epiblast?
At this point in the picture, what happens to the cells that remain of the epiblast?
Cells on top detach, migrate, and form the mesenchyme
The remaining cells form the ectoderm
The yellow that is directly under the mesoderm in the picture is from what? Is it from the hypoblast
So then where is the hypoblast?
No, it’s from the cells that migrated through the primitive streak
It’s the part that doesn’t directly underlie the mesoderm
What does the migrating mesoderm (the red in the picture) become?
Connective Tissue
The black boundary in the middle is also formed from migrating mesoderm, what structure does it form?
The notochord
In the picture, the mesoderm that migrates along either side of the notochord is called the…
Paraxial Mesoderm
In the picture below, what are I and S? Also note the location of the lateral plate mesoderm
Also, what is the space above the blue line?
- I is the lateral plate mesoderm
- S is the paraxial mesoderm
- The space is the amniotic cavity
What is the blue and the yellow in the picture below?
- Blue is ectoderm
- Yellow is endoderm
What does the intermediate mesoderm form most of?
The urinary and reproductive system
What is the name for the space that exists because of the split in the lateral plate mesoderm?
Intraembryonic Coelom
What is the function/purpose of the space between the blue (ectoderm) and the outer intermediate mesoderm?
Supports the body wall with muscle and connective tissue
What does the space between the mesoderms, formed by the lateral plate (the intraembryonic coelom) become?
Abdominal Cavity
What does the space between the endoderm (yellow) become?
Gut Tube
This is the term describing the part of the mesoderm that becomes the body wall
Somatopleure
This is the term for the mesoderm that lines the outer part of the gut tube
Splanchopleure
Identify the parts in this picture
Identify the parts in this picture
Identify the colored areas in this picture
Which contributes most to the development of the notchord, ectoderm, mesoderm, or endoderm?
Mesoderm
The notochord defines the ___ axis of the embryo
It induces the development of these two things
- Defines the primordial axis of embryo
- Induces the development of the neural plate
- Induces development of axial skeleton
What forms around the notochord?
What eventually happens to the notochord?
The vertebral column
It regresses and mostly disappears (except for intervertebral discs)
The notochord loses its epithelial connection and becomes attached to the..
It then loses it’s epithelial connections once more and what happens ?
Endoderm
Cells at the end compact and it becomes a rod (see picture)
The paraxial mesoderm forms the….
Somites
- These are the striated muscles of the body wall
- They divide into two parts
Myotomes
Epimere and hypomere
- During segmentation, what folds in and creates neural tube?
- What is within the neural tube (ventral to neural tube here)
- Ectoderm
- Notochord (ventral to NT here)
The somites divide into three parts, what are they?
- Scleratomes
- Myotome
- Dermatome
Which aspect of the somite becomes cartitlage, supportive tissues, vertebrae and ribs
Scleratomes
Which part of the somite forms muscles of body wall and limbs (trapezius, splenius, lats)
Myotomes
- The myotome divides into two parts, called…
- This is the dorsal part of the myotome
- This is the ventral part of the myotome
- Epimere and Hypomere
- Epimere
- Hypomere
This part of the myotome gives rise to the deep back muscles
Epimere
This part of the myotome forms the ventral muscles and superficial back
Hypomere
This part of the somite becomes the dermis
Dermatomes
Identify the lines in this picture
To form the dermis, the dermatomes join with what?
Somatopleure
Identify the lines in this picture
Scleretomes on either side grow towards one another, fuse, surround neural tube, form the…
Spinal Vertebrae
These divide in half, top and bottoms of different ones fuse with one another, creating ones
Why is this beneficial?
Scleratomes
It allows muscles to span vertebrae, creating movement
Also creates space for spinal nerves to travel
During neuration, as shown in the picture, what structure is folding out?
What does it form?
Ectoderm
Neural plate
During neurulation, what forms due to the rising of the lateral plate? The cells get thicker on at basal end but thinner at apical end
Neural groove and neural fold
At this point in the picture, the ectoderm is well positioned to form the ___ but not the _____
- Skin
- Brain
- When the neural folds reach eachother, where does fusion begin?
- What does this fold and fusion eventually form?
- In the middle, the fuses away from middle in cranial and caudal direction
- Neural Tube
What does the neural tube form?
CNS and somatic efferent (motor) neurons
Within the neural fold, these detach, migrate and become other nervous system processes (afferent neurons, dorsal root ganglia, much of ANS and ganglia, glial cells, many cells in endocrine and other body systems)
Neural crest cells
