Midterms_Ectodermal Derivatives Flashcards
The ectoderm is made up of these three main derivatives
Outer Ectoderm
Neural Crest
Neural Tube
What are the derivatives of the Outer Ectoderms
Lens
Epidermis
Mouth Epithelium
Olfactory Epithelium
Nails
Sebaceous Glands
Hair
What are the subderivatives of the mouth epithelium
Clue: CAT
Cheek epithelium
Anterior Pituitary
Tooth Enamel
What are the derivatives of the Neural Crest?
Dentine of Teeth
Adrenal Medulla
Melanocytes
Peripheral Nervous System
Facial Cartilage
What are the derivatives of the peripheral nervous system?
PNSS
Parasympathetic Nervous System
Neuroglial Cells
Schwann Cells
Sympathetic Nervous System
What are the derivatives of the Neural tube?
Spinal Cord
Motor Neuron
Brain
Retina
Neural Pituitary
True or False
The nervous system is made up of the central nervous system and the peripheral nervous system.
True
What is the CNS made of?
Brain and spinal cord
What is the PNS made of?
nerves and ganglia
The development of the nervous system differentiates from this structure at different organizations.
Neural Tube
The development of the nervous system differentiates from the neural tube at 3 LEVELS OF ORGANIZATION. Which are?
Organ Level
Tissue Level
Cellular Level
In the development of the nervous system, what is the level of organization where the neural tube bulges and constricts to form the different regions of the brain and spinal cord
Organ Level
In the development of the nervous system, what is the level of organization where cells on the walls of the neural tube rearrange themselves to form different functional regions of the brain and spinal cord
Tissue Level
In the development of the nervous system, what is the level of organization where the neuroepithelial cells differentiate into neurons and glial cells.
Cellular Level
T or F
In the cellular level of nervous system development, neural crest cells differentiate into neurons and glial cells
False: Neural crest, Neuroepithelial
T or F: In the development of the nervous system (cellular level), the POSTERIOR portion of the neural tube develops into the brain whereas the ANTERIOR portion develops into the spinal cord
False: Interchange posterior and anterior
What type of directional differentiation does the brain vesicles and brain flexures undergo?
Antero-posterior Differentiation
What are the two features that forms in antero-posterior differentiation.
Brain vesicles and brain flexures
This is a process of expansion (of the neural tube) to form primary vesicles.
vesiculation
What region does vesiculation occur?
Anterior region
The brain vesicles have cavities called?
ventricles.
The secondary ventricles are derived from?
primary ventricles.
Essay
How does the brain vesicles form?
At the anterior region, the neural tube undergoes vesiculation, a process of expansion or ballooning into three primary vesicles, the prosencephalon, mesencephalon, and rhombencephalon.
These primary vesicles eventually form secondary vesicles, which give rise to various adult structures.
The brain vesicles have cavities called ventricles.
The secondary ventricles are derived from the primary
ventricles.
What are the ventricles that make up Forebrain, Midbrain, and Hindbrain respectively?
Prosocoel, Mesocoel, and Rhombocoel
What do you call the smaller compartments of the rhombencephalon?
Rhombomeres
This brain structure is formed by the derivatives of the midbrain and hindbrain
Brainstem
These are clusters of neuronal cell bodies whose axons form a nerve
Ganglia
What forms the ganglia?
Rhombomeres
T or F
In Brain Flexures, The brain grows far more slowly than the membranous skull enclosing it, causing the brain to develop flexures.
False; slowly, rapidly
In Brain Flexures, the brain develops three flexures namely:
Cephalic
Pontine
Cervical
T or F
The Cephalic flexure is found between midbrain and hindbrain
False: Found between Forebrain and Midbrain
T or F
The cephalic flexures folds the forebrain dorsally
False: dorsally, ventrally
The cephalic flexure pushes the mesencephalon to what direction?
upwards
True or False
Pontine Flexures are Dorsal Flexures
True
Where are pontine flexures located?
Between Metencephalon and Myelencephalon
The pontine generates what type of ventricle?
Fourth Ventricle
The cervical flexures are found between?
Myelencephalon and spinal cord
The cervical flexures folds the brain in what direction relative to the spinal cord?
ventrally
Another result of limited space is that, as the cerebral hemispheres continue to grow and expand, they almost completely envelope what secondary vesicles?
Diencephalon and Mesencephalon
State all the secondary vesicles
CLUE: Tel Di Mes Met My
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myencephalon
Under the limited space from rapid brain growth, what structures form, that increase the surface area, allowing more neurons to occupy a limited space.
Convolution
Advantage of convolutions?
Increase surface area that allow neurons to occupy a limited space
T or F
The dorsoventral differentiation of the neural tube can be best understood by looking at the brain.
False: brain, spinal cord
The dorsal region of the neural tube receives input from what cells?
sensory neurons
What region of the neural tube receives input from sensory neurons?
dorsal region
What region of the neural tube does the motor neurons reside?
Ventral region
The region between the dorsal and ventral areas contains what cells?
interneurons
Purpose of interneurons?
Relay information between sensory and motor neurons
Fill in the Blank
Dorsal differentiation is influenced by __________ while ventral differentiation is induced by the __________.
- epidermis
- notochord
The epidermis BMP4 and BMP7 induce the dorsal most area of the neural tube to become what identity?
roof plate
What is the roof plate for?
It serves as a secondary signalling center
The roof plate also expresses what substance?
BMP4
What does BMP4 induce?
A cascade of TGF-β superfamily proteins
What does TGF-β superfamily proteins do?
Act as a morphogen
These signal molecules that diffuse from the source and form a concentration gradient.
morphogens
The concentration gradients of the TGF-β superfamily induce different types of what?
Transcription Factors
T or F
The concentration gradients of the TGF-β superfamily induce different types of vesicles in cells at different distances from the roof plate, giving them different identities.
False: vesicles, transcription factors
List the gradients of the following identities
• roof plate
• D1 interneurons
• D2 interneurons
• D3 interneurons
• BMP4, BMP5, BMP7, Dorsalin, Activin = roof plate
• BMP7, Dorsalin, Activin = D1 interneurons
• Dorsalin, Activin = D2 interneurons
• Activin = D3 interneurons
In ventral patterning, what is the substance secreted by the notochord?
sonic hedgehog (shh)
What does sonic hedgehog (shh) do?
induces the ventral most area of the neural tube to become the floor plate,
What is the function of the floor plate?
secondary signalling center
What acts as morphogens in ventral patterning?
sonic hedehog (shh)
T or F
The floor plate also expresses shh that acts as a morphogen, forming a gradient highest at the most anterior portion of the neural tube,
False: anterior, ventral
What signals the differentiation of different cell identities?
gradients
List their identities:
• Highest concentration of shh
• Decreasing concentrations from the floor plate
- floor plate
- V3 neurons
motor neurons
V2 interneurons
V1 interneurons
The neural tube is initially composed of a single layer called?
Germinal neuroepithelium
T or F
The germinal neuroepithelium is single layered
True
This is a mitotic neural layer surrounding the cavity (ventricle) of the neural tube
germinal neuroepithelium.
The germinal neuroepithelium is also known as?
ventricular layer or ependymal layer.
It is a pseudostratified layer whose cells divide vertically (instead of horizontally)
Germinal neuroepithelium, ventricular layer or ependymal layer.
In Neural Tissue; the ventricular layer or ependymal layer gives rise to two cells.
One cell remains close to the ventricle and remains as a what?
Stem cell
In Neural Tissue; the ventricular layer or ependymal layer gives rise to two cells.
The cells migrates away to become either what?
Neural stem cell and glial stem cell
Neural stem cells form what type of cells?
Neurons
Glial stem cells form what type of cells?
neuroglia
As the neuroepithelium divides, migrating cells form a second layer around the neuroepithelium called the?
mantle or intermediate zone.
As the neuroepithelium divides, migrating cells form a second layer called the mantle or intermediate zone around the neuroepithelium. The mantle differentiates into what type of cells?
neurons and glial cells
Neurons, from the differentiation of the mantle layer, establish connections with each other and send out axons away from the lumen, forming a cell-poor layer called?
the marginal zone
In the marginal zone, The glial cells ensheath these axons with myelin sheaths, giving them a whitish appearance thus referred to as?
White matter
In the marginal zone, the mantle layer that contains the neuronal cell bodies is then referred to as?
gray matter
What do you call neuronal precursors from the neuroepithelium?
Neuroblasts
Where do neuroblasts migrate to form neuron clusters?
white matter
What do you call clusters of neurons?
Nuclei
What is the function of the clusters of neurons (nuclei)?
relay stations between cerebellum and other parts of the brain
In the cerebellum, other neuroblasts from the neuroepithelium migrate to the outer layer surrounding the white matter to form a two-layered what?
External Granule Layer
What is the function of the external granule layer?
It is where neuroblasts proliferate
Neuroblasts of the inner layer of the external granule layer form granule neurons that migrate back to the white matter and form the?
Internal Granule Layer
neuroblasts of the inner layer of the external granule layer form what?
Granule neurons
As the neuroepithelial layer continues to generate more cells, it gives rise to large and distinctive?
Purkinje neurons
what doesthe purkinje neurons do?
migrate between the external granule layer and the internal granule layer forming the Purkinje cell layer
The Purkinje neurons have enormous processes called?
dendritic arbor
what is the purpose of dendritic arbor?
synapse with the neurons of the external granule layer
What part of the Purkinje neurons synapse with the neurons of the internal granule layer?
Long axons
Where does vertical and horizontal differentiation occur?
cerebrum
In vertical differentiation, neuroblasts from the mantle layer (grey matter) migrate outside the white matter to form the outer layer of the brain called the?
neocortex
The neocortex; this layer forms how many layers?
6 distinct layers
T or F
The cerebrum is organized vertically into over 40 regions with distinct functions
False: vertically, horizontally
Neural crest cells originate at what region of the neural tube?
dorsal
What do neural crests do to generate various types of cells?
migrate
Nural crest cells give rise to how many functional domains?
4 main functional domains
The first group of neural crest cells to separate from the neural tube and undergo epithelial to mesenchyme transition.
Cranial / Cephalic Neural Crest
neural crest cells from the forebrain and midbrain give rise to three structures; namely?
- Skeletal elements of the face
- Melanocytes
- Neurons and glial of the cranial ganglia
Neural crest cells from the rhombomeres give rise to three streams which are?
Trigeminal
Hyoid
Post-otic
FThis stream of neural crest cells fills in the 1st pharyngeal arch (PA1) and gives rise to the jawbones, odontoblasts of the teeth, malleus, and incus of the middle ear
Trigeminal Neural Crest
This stream of neural crest fills in the 2nd pharyngeal arch (PA2) and gives rise to the hyoid bone and stapes
Hyoid neural crest
This stream of neural crest cells fills in the 3rd pharyngeal arch (PA3) and contributes to the thyroid and parathyroid gland
Post-otic neural crest
T or F
Each of the neural crest streams gives rise to the cranial and pharyngeal ganglion
False: pharyngeal, jugular
What arises from the neural tube at the level of somites?
Vagal Neural Crest
What somite level form the parasympathetic (enteric) nervous system of the foregut?
Somite 1-3
In level of somites 1-3, some of the cells migrate to the heart thus called the?
cardiac neural crest
T or F
Cardiac neural crests contribute to the formation of the pulmonary semilaminar valves
False: semilaminar, semilunar
Level of somite produces this tissue of large arteries of the heart.
musculoconnective tissue
The cardiac neural crest populate what Pharyngeal arches?
3-6
T or F
Cardiac neural crest gives rise to melanocytes, neurons, and connective tissues of Pharyngeal Arches 1-3
False: 3-6
What somite level contributes to the enteric nervous system of the stomach?
Level of somites 4-6
What somite level contribute to the dorsal root ganglia of the peripheral nervous system and melanocytes
Level of somite 7
What neural crest originates posterior to the vagal neural crest.
Trunk neural crest
What trunk neural crest pathways is between the neural tube and the somites
ventrolateral
What do you call the derivatives of the somite?
ssclerotome
Trunk Neural Crest Cells that migrate up to the ___________ give rise to the sensory neurons and glial cells of the dorsal root ganglia of the peripheral nervous system
sclerotome
Trunk neural crest cells that migrate towards this pathway form the sympathetic ganglia, the adrenal medulla, and nerve clusters of the aorta. So what is this pathway?
ventrally
What Trunk neural crest pathway is between the ectoderm and anterior sclerotome?
dorsolateral
Dorsolateral pathway of the Trunk neural crest gives rise to what cells?
melanocytes
What arise at the posterior-most region of the neural tube?
Sacral Neural Crest
T or F
The sacral neural crest migrates ventrally and colonizes the gut giving rise to the enteric nervous system of the
foregut
False: foregut, hindgut
Eye development begins when vesicles bulge from each side of the diencephalon. what are these vesicles?
optic vesicles
As the optic vesicles continue to grow outward, it comes in contact with the ectoderm and induces the formation of this structure.
lens placode
The induced lens placode then invaginates forming this structure.
Lens pit
This invagination pushes against the optic vesicle, causing it to invaginate, too, forming a double-walled?
optic cup
What structure is the optic cup attached to?
narrow optic stalk.
The walls of the optic cup includes:
Outer and Inner wall
At what layer of the optic cup do cells produce melanin pigment?
Outer wall
In the outer walls of the optic cup, cells produce melanin pigment and the layer becomes the?
pigmented retina
At what layer of the optic cup do cells proliferate rapidly?
Inner wall
glial cells, ganglion cells, interneurons, and light-sensitive photoreceptor neurons all form what structure?
neural retina
Fill in the blank
In the inner wall of the optic cup, the optic stalk is now called?
optic nerve
In the development of the eye, the lens pit closes over itself forming what structure?
lens vesicle
In the development of the eye, The closed ectoderm then
differentiates into?
cornea
T or F
The optic vesicles arise from the Myelencephalon,
False: Myelencephalon, diencephalon
T or F
Since the optic vesicles arise from the diencephalon, the walls are then lined with the same germinal neuroepithelium of the neurologlia.
False: neurologlia, neural tube
Differentiation of the Neural Retina give rise to two layers, Which are?
Outer neuroblastic layer
Inner neuroblastic layer
What does the outer neuroblastic layer face?
pigmented retina
What does the inner neuroblastic layer face?
lens
In differentiation of the neural retina, from two layers, three layers of cells are formed, which are?
Outer, middle and inner layers
In differentiation of the neural retina, what layer comprises rods and cones phototoreceptors?
Outer layer
In differentiation of the neural retina, what layer comprises bipolar neurons?
Middle
In differentiation of the neural retina, what layer comprises ganglion cells?
Inner layer
In differentiation of the neural retina, point of synapsis between the neurons of each layer form the?
plexiform layers
T or F
In differentiation of the Lens, the lens vesicle is made up of a single layer of lens epithelium surrounding a lens cavity.
True
What induces the cells of the posterior epithelium
to transform into elongated, slender cells?
neural retina
What lens epithelium forms the primary lens fibers and crystallins?
Posterior epithelium
What do you call elongated slender cells transformed from the posterior epithelium?
primary lens fibers
What is tghe function of primary lens fibers?
fill in the cavity of the lens vesicle.
The cells of the posterior epithelium synthesize transparent, lens-specific proteins and lose their nuclei. What do you call these proteins?
crystallins
In the anterior epithelium, Cells at the equatorial region elongate towards the anterior and posterior areas and form the?
secondary lens fibers
What section of the len epithelium do secondary lens fibers form?
Anterior epithelium
This process begins when the mesenchyme that surrounds the external surface of the optic cup condenses.
Corneal differentiation
In corneal differentiation, the mesenchyme condenses into two layers, which are?
Choroid and sclera
This is the inner, pigmented, vascular layer of the mesenchyme
choroid
This is the outer, fibrous layer of the mesenchyme.
Sclera
In mesenchyme at the anterior of the developing lens, this is the inner layer that is continuous with the choroid.
Iridopupillay membrane
True or False
The Iridopupillay membrane will eventualy disappear.
What happens if Iridopupillay membrane dissappears?
allowing communication between the anterior and posterior
chambers of the eye
In the mesenchyme at the anterior of the developing lens, what do you call the outer layer that is continuous with the sclera?
Corneal stroma
This is a corneal layer that develops from the surface ectoderm.
Corneal epithelium
This is a corneal layer that is derived from the surrounding mesenchyme.
Corneal Stroma
This is a corneal layer that forms from neural crest cells that migrate from the rim of the optic cup
Corneal endothelium
T or F
The epidermis develops from the ectoderm after gastrulation.
False: gastrulation, neurulation
In the development of the epidermis, this is the outer layer that serves as a temporary covering
Periderm
T or F
The periderm merges once the true epidermis is formed.
False: merges, shed
In the development of the epidermis, this is the inner layer that is mitotic.
Basal layer/ Stratum germinativum
This strata gives rise to all the cells of the epidermis
stratum germinativum
The basal layer/stratum germinativum divides to form?
an intermediate layer
In the development of the epidermal cells the intermediate layer is between what?
periderm and basal layer
The intermediate layer forms numerous tonofilaments that connect adjacent cells making the layer look “spiny” thus called?
stratum spinosum
stratum germinativum and stratum spinosum are mitotic layers and collectively known as the?
Malphigian Layer
In the development of Epidermal Cells, Cells of the
Malphigian layer divide to produce what strata?
stratum granulosum
stratum granulosum is a layer that contains what granules?
keratohyalin
What are the precursor of keratin?
keratohyalin granules
The non-mitotic granular cells differentiate into
keratinized cells called?
keratinocytes
Keratinocytes comprises what strata?
stratum corneum
T or F
Stratum granulosum is a layer of flat cells
False: granulosum, corneum
Melanocytes from the neural crest invade the Malphigian layer and transfer their pigment sacs to developing keratinocytes. What do you call these pigment sacs?
melanosomes
T or F
When epidermal derivatives form, they grow downward and penetrate the fatty tissues.
False: fatty tissues, dermis
What do you call the derivative of the mesoderm?
dermis
The development of hair occurs in how many stages?
3
What are the three stages of hair develoment?
Clue: IOC
Induction
Organogenesis
Cytodifferentiation
What induces the epidermal cells of the of the basal layer to become columnar and bulge slightly into the dermis?
fibroblast cells,
The epidermal cells of the of the basal layer to become columnar and bulge slightly into the dermis as?
hair placode
In Organogenesis (Hair Development), the cells continue to proliferate and form clusters which enlarge and elongate to
generate the?
hair germ
In organogenesis, the dermal fibroblasts respond to the “sinking” of the hair germ and form a small node beneath the hair germ forming the?
dermal papilla
T or F
The dermal papilla pushes against the “sinking” hair germ, stimulating the hair germ further to divide and envelope the dermal papilla
True
In cytodifferentiation, the hair germ cells give rise to post-mitotic cells that will differentiate into what keratinized structure?
hair shaft
In Cytodifferentiation, two epithelial swellings or bulges grow on the sides of the hair germ which are?
Lower and Upper Swelling
This epithelial bulge retains the population of stem cells and will generate the hair shaft periodically
lower swelling
This epithelial bulge forms the sebaceous gland
uper swelling
