Embryology Flashcards
At this point of gastrulation (trilaminar embryo) the embryo starts to form three distinct layers. The blue which is the most outer part is the (ectoderm/mesoderm). The red which is the middle part is the (ectoderm/mesoderm). The last layer deep inside which is the orange layer is the (ectoderm/endoderm).
ectoderm; mesoderm; endoderm
The (ectoderm/mesoderm) is going to differentiate into the CNS and PNS.
ectoderm
The (CNS/PNS) contains the somatic, autonomic, and enteric systems.
PNS
Things like the radial nerve, musculocutaneous nerve, and the things that are telling the muscles what to do, the things that are telling the brain what we are feeling from the skin and the ligaments are part of the (autonomic/somatic) portion of the PNS.
somatic
The sympathetic and parasympathetic are part of the (autonomic/somatic) nervous system which is from the PNS.
autonomic
The (autonomic/enteric) part of the PNS is the part that is going to our inner organs and trying to keep the body at homeostasis.
enteric
The other part the ectoderm is going to differentiate to is the _____ which contains hair, nails, mammary & subcutaneous glands.
epidermis
The (mesoderm/endoderm) is the area that is going to differentiate into the connective tissue (cartilage and bone) and muscle (striated and smooth (heart, kidneys, gonads, and spleen)).
mesoderm
The (mesoderm/endoderm) contains the GI system and the respiratory system.
endoderm
In human beings in about 18 days after fertilization of the egg, the ectoderm starts to fold up a little bit and you get the _____ plate. There is a structure that is embedded in the mesoderm called the ______ and this structure is critical to the organization of the human being, the animal, the CNS, and all the PNSystems that are coming into play.
neural; notochord
The notochord after getting to a certain level of development releases a protein that starts to signal the middle part of the ectoderm to start changing into something that is called the _____, which is going to be turning into the (CNS/PNS). The middle most aspect of that ectoderm is what is turning into the (CNS/PNS). Everything else in blue is going to be turning around and shaping the protective structures of the skeletal system and the skin that is going to be surrounding that neural structure.
neural plate; CNS; CNS
At roughly 20 days the neural plate folds in on itself. The middle part turns into the (CNS/PNS). The structure folds in and the neural tube turns inward and the top edge comes around and wraps around to form the protective layer of skin while the tube that has developed becomes the (CNS/PNS).
CNS; CNS
The outer edges are the _______ cells because they sit on the crest of that ridge and those outer layers are going to come into contact with each other and pinch in together. As the embryo keeps going through development those _____ cells are going to separate from the tube that we have and that tube is going to become the (CNS/PNS). Those crest cells that have separated away from that main tube become the _____, ________, facial bones, smooth muscles, pigment cells, and connective tissue.
neural crest cells; neural crest; CNS; PNS; dorsal root ganglia
As we keep going through this embryonic development stage the (ectoderm/mesoderm) starts to separate out and gets itself prepared to become skeletal muscle and is sitting pretty close to where those ____ cells are because we need innervation of those muscles.
mesoderm; crest
In terms of organization of the CNS, whether it’s the spinal cord or the cerebrum. The further that body is from the notochord, its going to differentiate into the (motor/sensory) system. The closer that structure is to the notochord, its going to develop to the (motor/sensory) system.
sensory; motor
As we go through development and the human being is formed and created, the notochord is actually going to become the (annulus fibrosus/nucleus pulposus) within the vertebral bodies.
nucleus pulposus
In starter cells there are _____ cells, _____ cells, and _____ cells. These are the cells that are going to differentiate into courtesies and into basal ganglia. All of these things are there to set the stage to be a cellular backbone for the (CNS/PNS) as it is developing.
precursor, progenitor, and stem; CNS
Three weeks (22 days) into the gestational period we have a slightly more well-developed structure and that center matrix (the green part) starts to form more of a tube-like structure. The somites, which sit side by side are coming off of the (ecotderm/mesoderm) and that is what is going to differentiate into the muscles.
mesoderm
At about day 24 we have a tube that is open on both ends. Our CNS is not open at both ends, the brain is not open, and the spinal cords not open. At day 24 the ______ and the _______have to close. If those structures do not close, we start running into congenital disorders.
anterior neuropore; posterior neuropore
If the (anterior/posterior) neuropore does not close we can get things like spinal bifida. If the (anterior/posterior) neuropore does not close, we run into a situation called anencephaly which is when the baby is born without a cerebrum.
posterior; anterior
The (anterior/posterior) neuropore is going to become the cerebrum.
The (anterior/posterior) neuropore is going to become the end of the spinal cord.
anterior; posterior
As these somites are beginning to turn into muscle, vertebral body, bone, ligaments, cartilage, and as this ectoderm is starting to differentiate into skin, those crest cells that have broken off that are sitting along that tube are starting to reach out and make connections with these regions to make the ______, _______, and the _______.
dermatomes, myotomes, and sclerotomes
Ventral is synonymous with (anterior/posterior).
Dorsal is synonymous with (anterior/posterior).
anterior; posterior
Rostral is synonymous with (superior/inferior).
Caudal is synonymous with (superior/inferior).
superior; inferior
At a certain point in development, that tube starts to go through flexors and it is going to bend three times. As it bends, that tube that we had starts to differentiate into a structure called the _____, the ________, and the ________ which is the 3 vesicle stage. That bend is necessary because we have a vertically descending spinal cord versus an anterior to posterior traveling spinal cord.
mesencephalon, prosencephalon, and the rhombencephalon
After more development that tube is going to bend one more time and what is going to happen is the prosencephalon is going to differentiate into two structures referred to as the ______ and ______ . The mesencephalon is going to stay the mesencephalon and will turn into what we call the (hindbrain/midbrain). The rhombencephalon is going to differentiate into the _______ and the _______ . So it is just further differentiation into five different neural structures which is the 5 vesicle stage.
diencephalon and telencephalon; midbrain; myelencephalon; metencephalon
Because of that bend that happens, for the cerebrum the top is (dorsal/ventral) and the bottom is (dorsal/ventral).
dorsal; ventral
When we get to the brainstem and cord the back is (dorsal/ventral) and the anterior aspect is (dorsal/ventral).
dorsal; ventral
At this point (3 vesicle embryo stage) and through this whole stage, this is a tube and the inside is hollow. That hollow tube is essential for the function of the (CNS/PNS) and the ____ cord. These are referred to as vesicles at this point in the game. Vesicle just means an empty container.
CNS; spinal
The prosencephalon is synonymous with the (forebrain/midbrain).
The mesencephalon is synonymous with the (forebrain/midbrain).
The rhombencephalon is synonymous with the (forebrain/hindbrain).
forebrain; midbrain; hindbrain
In terms of differentiation of this tube into what we recognize as the cerebral cortex, there are starter cells within that neural tube and what happens is, as development continues to occur, there is a process called _______ which is the creation of the cerebral cortex. It starts from inside that neural tube and expands out.
corticogenesis
There are three zones as we start to develop into a cortex. The first zone is called the (ventricular/intermediate) zone and that is the area closest to the lumen of the tube. Within that ventricular zone there are (precursor/stem) cells (neuroblasts and glioblasts).
ventricular; precursor
The cell bodies travel into the cortical plate from the (intermediate/ventricular) zone.
ventricular
The cortical plate becomes the ____.
cortex
The (intermediate/ventricular) zone has radial processes and white matter.
intermediate
In the cerebrum and the cortex the outer layer is the (grey/white) matter and the inner layer is the (grey/white) matter.
grey; white
The gray matter is primarily (axons/cell bodies) and the white matter is all (axons/cell bodies).
cell bodies; axons
_____ defects are defects that happen in development of the organism whether it’s a human or primate and they are congenital birth issues. And the most serious of them all is failure to close of the (anterior/posterior) neuropore.
Dysraphic; anterior
When there’s failure to close of the anterior neuropore you get what is celled _______ which is failure of the cerebrum to form. There is a 100% first year mortality rate because if you don’t have the cerebrum there to control for certain aspects the organism is not going to thrive.
anencephaly
Spina bifida occurs when the (anterior/posterior) neuropore does not close. So there is an opening that is going to impact either the spinal cord or the vertebral bodies that are surrounding the spinal cord.
posterior
Spina bifida occulta is where the cord is intact and the dura is pretty well intact but what is missing is some form of _______ arch so you don’t have closure of that structure along the spinal column.
vertebral
In spina bifida occulta, (musculoskeletal/neurologically) they are mostly asymptomatic, in terms of (musculoskeletal/neurologically) they may have some symptoms, and you may see skin changes along the dorsal aspect.
neurologically; musculoskeletal
In spina bifida cystica (meningocele/myelomeningocele) the spinal cord is still intact but there is this bubble around the dura because there is more fluid that is starting to collect within that meningeal space within the dura and the vertebral arch is missing. In meningocele, you start to see a little more neurologic features because the bottom end of that spinal cord could potentially be getting deformed because it is a soft structure.
meningocele
Spina bifida cystica (meningocele/myelomeningocele) occurs when the meninges along with CSF herniate through the posterior vertebral arch defect. The sac contains meninges and Cerebrospinal fluid CSF.
meningocele
In Spina bifida cystica (meningocele/myelomeningocele) it is typically covered with skin, they may have bowel/bladder dysfunction due to impaired sacral myotomes, and they may have lower extremity myotomal deficits.
meningocele
Spina bifida cystica (meningocele/myelomeningocele) has all of the similar mechanisms but the sac which contains meninges, CSF AND the spinal cord is getting wrapped up and involuted in that bubble, so there Is a much higher likelihood of neurological dysfunction depending on the level and processes going on.
myelomeningocele
Spina bifida cystica: (meningocele/myelomeningocele) is the most severe form of posterior pore dysraphism and there is a genetic disposition. There is a genetic predisposition with metabolism of folic acid, so by simply enhancing a pregnant mothers intake of _____ acid this can be a very avoidable situation.
myelomeningocele; folic
