Lesson 10 Flashcards
This is the part of the nervous system that develops from the ectoderm, once it has differentiated into surface ectoderm and neuroectoderm.
Central Nervous System (CNS)
This part of the nervous system develops in association with the CNS and serves as the communication system between the CNS and the rest of the body.
Peripheral Nervous System (PNS)
This embryonic structure, formed from cells that invaginate and move towards the cranial end, eventually forms the notochord.
Primitive Node
This signaling molecule, essential for CNS development, signals the notochord to induce overlying ectodermal cells to differentiate into neuroectoderm.
Sonic Hedgehog
These molecules act between cells within close range and are involved in induction and embryonic cell patterning.
Paracrine Factors (or Morphogens)
This thickening of the ectoderm represents the primordium of the nervous system and is induced by the notochord.
Neural Plate
The process that ends with the formation of the neural tube involves these cells detaching from the neural tube, which are essential for PNS formation.
Neural Crest Cells
This is the process by which the neural plate folds to form a structure that will later develop into the CNS.
Neurulation
This structure is initially formed as a flattened tube that becomes the notochordal plate and eventually reforms into a tube to become the notochord.
Notochord
These are the two subdivisions of the ectoderm that form during the early stages of nervous system development.
Surface Ectoderm and Neuroectoderm
This embryonic structure acts as a signaling center, inducing the overlying ectoderm to begin forming nervous system structures.
Notochord
This structure forms from the neural plate and serves as the precursor to both the brain and spinal cord in the CNS.
Neural Tube
his term describes a series of steps where undifferentiated cells are guided to develop specific structures through signals such as Sonic Hedgehog.
Induction
These types of cells are essential in embryonic development, particularly in cell differentiation and spatial organization. They include Sonic Hedgehog and act locally between cells.
Morphogens
This process involves ectodermal cells differentiating and thickening to form the neural plate, under the influence of signals from the notochord.
Neural Induction
This signaling molecule is a well-known morphogen that plays a critical role in establishing the dorsal-ventral axis in developing neural structures.
Sonic Hedgehog
This gene was named by Robert Riddle after his wife saw an advertisement for a famous video game.
Sonic Hedgehog
This structure, positioned near the midline neural plate, releases Sonic Hedgehog molecules to aid neural development.
Notochord
This protein, produced by the surface ectoderm during gastrulation, prevents the dorsal ectoderm from forming neural tissues.
Bone Morphogenetic Protein-4 (BMP4)
These two molecules act as neural inducers by blocking BMP4, allowing the dorsal ectoderm to form neural tissue during neurulation.
Noggin and Chordin
This term refers to the single layer of cells that make up the neural plate and the neural tube before neurogenesis begins.
Neuroepithelium
Shortly after neural induction, this layer organizes into a structure that appears stratified but is actually a single layer due to its closely packed cells of different sizes.
Pseudostratified Epithelium
During the cell cycle, these structures within neuroepithelial cells shift extensively in the cytoplasm and migrate toward the lumen of the neural tube.
Nuclei
This structure, formed after the neural plate folds, is crucial to the development of the central nervous system and undergoes extensive cellular migration and division.
Neural Tube
When the cleavage plane is perpendicular to the apical surface of the neural tube, these cells migrate to the tube’s periphery for DNA synthesis.
Daughter Cells
This term describes the orientation of a dividing cell’s structure that determines the fates of its daughter cells within the neural tube.
Mitotic Spindle
When the cleavage plane is parallel to the apical surface of the neural tube, the daughter cell closer to this surface remains capable of mitosis and is considered a proliferative progenitor cell.
Inner (Apical) Surface
The daughter cell closer to the basal surface of the neural tube, which inherits a high concentration of a receptor regulating cell differentiation, is called this.
Neuroblast
These are the precursor cells of neurons that eventually develop cell processes, forming axons and dendrites.
Neuroblasts
This receptor regulates cell differentiation in neuroepithelial cells and plays a role in determining the fate of cells during neural development.
Notch Receptor
This molecule is secreted by cells of the notochord to override BMP4’s inhibitory effects, allowing neural tissue formation in the ectoderm.
Noggin and Chordin
This structure, a midline rod of cells, serves as a central signaling center during early neural development by releasing molecules like Sonic Hedgehog.
Notochord
This protein, produced by surface ectoderm cells, initially prevents neural development in the ectoderm by inhibiting the formation of neural tissue.
Bone Morphogenetic Protein-4 (BMP4)
This term refers to neural cells in development that are pluripotent/multipotent and capable of self-renewal through mitotic divisions, eventually maturing into progenitor cells.
Stem Cells
These progenitor cells can give rise to either neuronal or glial cell lineages during CNS development.
Neural Progenitor Cells
These structures are the cellular projections formed by neuroblasts that will become part of neurons, allowing them to connect and communicate.
Answer: Axons and Dendrites
Neuroblasts that extend branches, forming primitive dendrites, are called this type of neuroblast, which will eventually mature into neurons with multiple extensions.
Multipolar Neuroblasts
Once formed, these cells lose their ability to divide and will differentiate further by extending small processes from the cell body, forming primitive axons and dendrites.
Neuroblasts
This type of progenitor cell, derived from neuroepithelial cells after neuroblasts stop being produced, gives rise to various types of glial cells.
Glioblasts
These cells form from O2-A progenitor cells and create the myelin sheath around axons in the CNS.
Oligodendrocytes
These cells, derived from O2-A progenitor cells, play a role in homeostasis and the formation of synapses in the CNS.
Astrocytes
These cells form a framework in the brain that guides migrating neurons during development.
Radial Glial Cells
This layer surrounds the ventricular zone in the spinal cord and becomes the gray matter as development progresses
Intermediate (or Mantle) Layer
As the neural tube thickens and appears layered, these cells in the neuroepithelial layer become the lining of the central canal and the ventricular system of the brain.
Ependymal Cells
These cells, acting as motile macrophages, originate from outside the neuroepithelium and become active after CNS damage.
Microglia
This layer forms on the periphery of the spinal cord and becomes the white matter as neuroblasts develop axons and dendrites.
Marginal Layer
These are dorsal thickenings on either side of the neural tube during spinal cord development.
Alar Plates
These are ventral thickenings on either side of the neural tube during spinal cord development.
Basal Plates
The left and right alar plates are connected dorsally by this structure.
Roof Plate
These cells, originating from the edges of the neural folds, give rise to sensory ganglia of the spinal nerves, Schwann cells, and various other cell types.
Neural Crest Cells
This term describes the process in which the spinal cord, initially spanning the entire embryo, is later outgrown by the vertebral column, leaving the spinal cord’s posterior end within the column.
Ascensus Medullae Spinalis
This term refers to the extensive branching seen in neurons as they form dendrites and establish connections.
Arborization
In adult animals, the spinal cord terminates at these vertebral levels, though this varies slightly by species.
L2 to L3
Which part of the neural tube eventually forms the brain?
The anterior two-thirds of the neural tube.
This initial expansion at the rostral end of the neural tube gives rise to the first brain vesicle.
Prosencephalon (or forebrain).
Which structures emerge as evaginations from the prosencephalon, contributing to visual system development?
Optic vesicles.
Which structures does the telencephalon ultimately form?
Cerebral hemispheres and olfactory bulbs.
What are the three primary brain vesicles formed by the neural tube?
Prosencephalon, Mesencephalon, and Rhombencephalon.
What two secondary vesicles does the prosencephalon divide into?
Telencephalon and Diencephalon.
Name the parts of the diencephalon that develop during brain formation.
Epithalamus,
Thalamus,
Metathalamus,
Hypothalamus, neurohypophysis, and
Optic cups.
This portion of the brain is essential for coordinating movements and originates from the metencephalon.
Cerebellum
What two structures develop from the rhombencephalon?
Metencephalon (pons and cerebellum) ,and
Myelencephalon (medulla oblongata).
How is cerebellar development at birth related to an animal’s ability to stand and walk shortly after birth?
Animals with a more differentiated cerebellum at birth, such as calves and foals, can stand and walk soon after birth.
And carnivores like puppies and kittens require additional postnatal development.
What essential bodily functions are regulated by centers located within the medulla oblongata?
Respiration and heartbeat.
This thin layer of ependymal and mesenchymal cells forms the roof plate of the myelencephalon, contributing to the creation of this structure, which produces cerebrospinal fluid.
Choroid plexus.
This flexure, occurring between the hindbrain and the spinal cord, aids in shaping the hindbrain.
Cervical flexure
The cephalic flexure is located between the forebrain and midbrain. Which brain vesicle does it impact?
Mesencephalon
Which part of the neural tube develops into the spinal cord’s white and gray matter?
The marginal layer becomes white matter, and the mantle layer (or intermediate layer) becomes gray matter.
It bends the forebrain down toward the brainstem
cephalic flexure
How does the formation of the choroid plexus relate to cerebrospinal fluid production?
The vascular mesenchyme invaginates to form the choroid plexus in the brain’s ventricles, which produces cerebrospinal fluid.
In the rhombencephalon, a dorsal bending called this flexure causes a thinning of the hindbrain’s roof in the future pontine region
Pontine flexure.
What is the role of Schwann cells, and from which cells do they originate?
Schwann cells form the myelin sheath in the PNS, originating from neural crest cells.
The telencephalon expansion leads to which major brain regions
The cerebral hemispheres and olfactory bulbs.
What two structures connect the left and right alar plates and the left and right basal plates?
The roof plate connects the alar plates dorsally, and the floor plate connects the basal plates ventrally.
(grooves and elevations) begin forming on the cerebral hemispheres later in fetal development, varying by species based on birth maturity.
Sulci (grooves) and gyri (elevation)
This part of the nervous system regulates many involuntary functions of the body, including the innervation of smooth muscle, cardiac muscle, exocrine, and endocrine glands.
Autonomic nervous system (ANS)
This part of the nervous system includes the brain and spinal cord.
Central nervous system (CNS)
This part of the nervous system includes all neural tissue outside the brain and spinal cord, extending throughout the body.
Peripheral nervous system (PNS)
This portion of the autonomic nervous system originates from the thoracolumbar region and is responsible for the “fight or flight” response.
Sympathetic nervous system
This portion of the autonomic nervous system originates from the cranial and sacral regions and is responsible for the “rest and digest” response.
Parasympathetic nervous system
This flexure results from a ventral bend between the hindbrain and the spinal cord.
Cervical flexure
These are the nerve fibers responsible for carrying signals from the autonomic nervous system to visceral organs, including smooth muscle and glands.
General visceral efferent fibers
As head folding occurs, this flexure is created by the mesencephalon bending ventrally.
Midbrain (cephalic) flexure
In the developing brain, this structure’s lumen expands and forms into well-defined chambers filled with cerebrospinal fluid (CSF).
Ventricular system
This fluid, produced within the ventricles, plays a crucial role in protecting and nourishing the brain.
Cerebrospinal fluid (CSF)
This nervous system division consists of cranial, spinal, and visceral nerves and is outside the central nervous system.
Peripheral nervous system (PNS)
Nerve fibers in this classification carry sensory impulses from the body toward the CNS.
Afferent (sensory) nerve fibers
Nerve fibers in this classification conduct impulses away from the CNS to the body.
Efferent (motor) nerve fibers
Peripheral nerves that terminate in tissues derived from the splanchopleura belong to this category.
Visceral nerves
Peripheral nerves that end in tissues from the somatopleura are classified as this.
Somatic nerves
These fibers receive sensory information from vision, hearing, and balance receptors.
Special somatic afferent fibers (SSA)
These fibers provide motor innervation to voluntary muscles derived from the somatopleura.
General somatic efferent fibers (GSE)
These nerves are classified as special afferent nerves and are responsible for the senses of smell, sight, and hearing.
Cranial nerves I (olfactory),
II (optic), and
VIII (vestibulocochlear)
This subset of cranial nerves is considered “mixed,” with both sensory and motor functions associated with the pharyngeal arches.
Cranial nerves V (trigeminal),
VII (facial),
IX (glossopharyngeal),
X (vagus), and
XI (accessory)
These cranial nerves contain only general somatic efferent fibers, providing motor function to specific skeletal muscles.
Cranial nerves III (oculomotor),
IV (trochlear),
VI (abducent), and
XII (hypoglossal)
These afferent fibers receive sensory information from the skin, skeletal muscles, and joints.
General somatic afferent fibers (GSA)
These afferent fibers receive sensory information from the viscera, or internal organs.
General visceral afferent fibers (GVA)
These efferent fibers provide motor innervation to skeletal muscles derived from the pharyngeal arches
Special visceral efferent fibers (SVE)
These afferent fibers receive sensory input from the retina, cochlea, and vestibular apparatus.
Special somatic afferent fibers (SSA)
These efferent fibers provide motor innervation to skeletal muscles.
Answer: General somatic efferent fibers (GSE)
These fibers provide motor control to smooth muscle and glands, often as part of autonomic functions.
General visceral efferent fibers (GVE)
Sonic hedgehog, a signaling molecule.
They signal the notochord to induce
overlying ectodermal cells to -?
neuroectoderm
The development of the neural plate (a
thickening of the ectoderm) that represents the p____ of the n____ s____
primordium of the nervous system
BMP4 prevents the d___ e___
from forming neural tissue.
dorsal ectoderm
The notochord, which is in close proximity to the m___ n___ p___ during this stage, releases sonic hedgehog molecules.
midline neural plate
During this stage, cells of the developing
notochord secrete noggin and chordin.
Neurulation
These two molecules are neural inducers
that block the inhibitory influence of BMP4 and thus allow the ectoderm dorsal to the notochord to form neural tissue.
Noggin and Chordin
Organizer molecules (The three in the picture of slide 20)
Noggin, Chordin and Follistatin
Before this process called ____, the neural plate and the neural tube are composed of a single layer of neuroepithelial cells
(neuroepithelium).
neurogenesis
They closely packed cells that
appear to be arranged in layers because
they’re different sizes, but there’s actually just one layer of cells.
Pseudostratified epithelium
Before neurogenesis, the___ ___and the __ ___ are composed of a single layer of ____ cells.
Clue: Shortly after induction, they organizes into a pseudostratified epithelium
the neural plate and neural tube; neuroepithelial cells
The orientation of cell division (the mitotic spindle) within the neural tube decides the future of each daughter cell:
In this plane, the Cells produced move outward to prepare for another DNA synthesis cycle.
Perpendicular Plane
In Parallel plane, the one daughter cell remains near the inner surface and stays as a ____ ___ that is capable of further division
progenitor cell
The other daughter cell, closer to the outer (basal) surface, inherits n____ r____ and becomes a n____
Notch receptor; neuroblast
They are precursor cells to neurons and can extend to form axons and dendrites.
Neuroblasts
long extensions from neuroblasts that transmit signals away from the cell body
Axons
are shorter, branched extensions that receive signals from other neurons.
Dendrite
Axons are guided to their correct destinations by specialized molecules and g__ c___.
growth cones.
Once axons reach their destinations, they form s____
- points of contact where they communicate with other neurons or muscle cells through the release of neurotransmitters.
synapses
the process by which Schwann cells (in the PNS) and oligodendrocytes (in the CNS) wrap around axons to form a myelin sheath.
myelination
TRUE OR FALSE?
The posterior (caudal) end of the tube becomes the spinal cord.
The anterior (cranial) end of the neural tube enlarges to form the brain.
TRUE
The neural crest cells migrate throughout the embryo after detachment to the neural tube, where they differentiate into various cell types which are __
sensory neurons,
autonomic neurons, and
Schwann cells.
In later stages,___ (formation of new neurons) and ______ (formation of glial cells, which support and protect neurons)
neurogenesis ; gliogenesis
Cranial Nerves that are special afferent functions.
Cranial nerves I (olfactory),
II (optic) and
VII (vestibulocochlear)
Cranial nerves that are general somatic efferent nerves.
Cranial nerves III (oculomotor),
IV (trochlear),
VI (abducent), and
XII (hypoglossal)
Classified as mixed nerves with both special visceral efferent and afferent components?
Cranial nerves V (trigeminal),
VII (facial),
IX (glossopharyngeal),
X (vagus), and
XI (accessory)
T OR F?
By convention, roman numerals are used to
designate the cranial nerves, with cranial
nerve I being the most rostral and cranial
nerve XII the most caudal
TRUE
Cranial nerves can be classified into three
categories:
- nerves with special sensory function (afferent)
- mixed nerves that innervate pharyngeal arch derivatives
- nerves with exclusively general somatic efferent fibers
Visceral efferent fibers control the
movement of ??
- voluntary muscles derived from the pharyngeal arches
- involuntary muscles and glands in the pulmonary and digestive tracts
- the cardiovascular system
a major differences between cranial and spinal nerves is the tendency of many cranial nerves to be either afferent or efferent rather than mixed.
TRUE
General somatic efferent fibers are concerned with voluntary muscles derived from the ____?
somatopleura.
Efferent as well as afferent nerves of the PNS
can also be classified as being ___ or ____.
somatic or
visceral.
Special somatic afferent fibers are
concerned with __,___and ___.
vision, hearing, and balance
In efferent and afferent nerves,
This subdivision is based on whether a peripheral nerve terminates in tissues derived
from the ____ or ____ .
splanchopleura (i.e. visceral tissue),
or somatopleura (i.e. body wall tissue)
T OR F?
The peripheral nervous system (PNS),
consists of the cranial, spinal, and visceral
nerves and the cranial spinal, and
autonomic ganglia.
TRUE
