Lecture 16 (Exam 2) Flashcards
The early neural epithelium is made of what type of epithelial cells?
Simple cuboidal
The neural plate is made up of what type of epithelial cells?
Simple columnar epithelium
The early neural tube wall is made up of __________ epithelium. This means it has a single layer of columnar cells with nuclei at varying heights.
Pseudostratified
The early neural tube wall has limiting membranes. The external limiting membrane is the ______ ______.
Basal lamina
The late neural tube is made up of _________ epithelium.
Stratified
Nuclei within the neural epithelium move from a position next to the _______ to a position next to the external limiting membrane. _______ occurs close to the lumen, while ______ ______ occurs close to the external limiting membrane.
Lumen
Mitosis
DNA replication
In the neural tube, if the metaphase plate of neural epithelial cells is (PERPENDICULAR/PARALLEL) to the inner margin of the neural tube (next to lumen), two resulting daughter cells will remain proliferative.
Perpendicular
In the neural tube, if the metaphase plate of neural epithelial cells is (PERPENDICULAR/PARALLEL) to the inner margin, daughter cells closest to the lumen will remain proliferative and daughter cells further from the lumen will become a neuroblast.
Parallel
In the daughter cells from a parallel metaphase plate that are farther from the lumen, they will express ______ receptor then become postmitotic. After this, they will move to the external limiting membrane and become a neuroblast (pre-neuron).
Notch
In the embryo spinal cord cross-section, the ependymal zone is also known as the ________ zone. The mantle layer is also known as the ________ zone.
Ventricular
Intermediate
In ventral signaling, the notochord induces formation of the floor plate of the neural tube via ________.
Shh (Sonic hedgehog)
Shh (Sonic hedgehog) produced by the floor plate induces the formation of ______ ______.
Motor neurons
In dorsal signaling, ectoderm flanking the neural plates uses ______ to induce ______ in the future neural crest and later to maintain ______ and ______ to create a dorsalizing effect.
BMPs
snail-2
Pax-3
Pax-7
In dorsal signaling, expression of Pax-3 and Pax-7 is suppressed by _______ from the floor plate to suppress the dorsalizing effect in the basal plate.
Shh
In dorsal signaling, expression of Pax-3 and Pax-7 is suppressed by _______ from the floor plate to suppress the dorsalizing effect in the basal plate.
Shh
In mammals, the primitive node and the notochordal process act as the primary inductors of the ________ system.
Nervous
The cranial end of the neural tube divides into a ________ brain.
Tripartite
The caudal part of the early brain becomes subdivided into segments (neuromeres), of which the _________ are most prominent.
Rhombomeres
Specific ________ genes are expressed in a regular order in the rhombomeres.
Homeobox
The isthmic organizer (a signaling center) is located at the junction between the midbrain and the hindbrain and acts by the production of ______ anteriorly and ______ posteriorly.
Wnt-1
FGF-8
Most cranial ______ are associated with the caudal end of the brain.
Nerves
Most structures supplied by the cranial nerves are derived from the ________ ________.
Pharyngeal arches
Cranial Nerve _____ (rhombomere 2 in birds) innervates structures derived from the first pharyngeal arch. The progeny of a single neuroblast remain within rhombomere 2. Axons of rhombomere ____ join those of rhombomere 2.
V
3
Cranial Nerve _____ (rhombomere 4 in birds) innervates structures derived from the second pharyngeal arch. The progeny of a single neuroblast remain within rhombomere 4. Axons of rhombomere ____ join those of rhombomere 4.
VII
5
Cranial Nerve _____ (rhombomere 6 in birds) innervates structures derived from the third pharyngeal arch. The progeny of a single neuroblast remain within rhomobmere 6. Axons from rhombomere _____ join those of rhombomere 6.
IX
7
Cranial nerves that innervate ________ structures (as opposed to splanchnic structures) arise in a different cranio-caudal column and do not occupy continuous rhombomeres.
Somatic
The segmented nature of spinal nerves is due to the pattern of somitic ________ along the neural tube.
Mesoderm
Motor neurons can penetrate (POSTERIOR/ANTERIOR) mesoderm of somites but not (POSTERIOR/ANTERIOR) mesoderm of somites.
Anterior
Posterior
This is a signaling center located between the mesencephalon and the metencephalon.
Isthmic organizer
The principal signaling molecule of the isthmic organizer is ______.
FGF-8
In the isthmic organizer, FGF-8/Wnt-1 induce the expression of…
En-1
En-2
Pax-2
Pax-5
The concentration of the gene products expressed by isthmic organizer will (INCREASE/DECREASE) as they move away from it.
Decrease
This isthmic organizer organizes and polarizes dorsal _______ and _______.
Midbrain
Cerebellum
Dorsoventral patterning of midbrain is primarily due to ______ located ventrally. This restricts the expression of ______ and similar molecules.
Shh
Pax-7
Pax-7 is related to the formation of ______ ______.
Alar plate
Pax-6 is expressed in alar plate of diencephalon and is “master gene” of _____ formation.
Eye
Pax-6 inhibits _____ and vice-versa. This reciprocal inhibition results in the formation of the diencephalic-mesencephalic border.
En-1
Forebrain segmentation is represented by an unremarkable set of three _________.
Prosomeres (P1-P3)
P1-P3 define the _________ and P2-P3 define dorsal and ventral _______.
Diencephalon
Thalamus
The secondary rhombencephalon field is a large area of the forebrain cranial to ____ and represents the prechordal region of the neural tube.
P3
The basal plate develops into the…
Hypothalamus
The alar plate develops into the…
Cerebral cortex
Basal nuclei
Optic vesicles
Axons grow out from the motor _________ located in the basal plate of the spinal cord.
Neuroblasts
Boundary caps created by ______ ______ cells maintain separation between central nervous system components and peripheral nervous system components.
Neural crest
Cells bodies of sensory neurons are derived from ______ ______ cells.
Neural crest
Cell bodies of sensory neurons form sensory ______ ______.
Spinal ganglia
Axons grow from sensory neuron cell bodies both toward the ______ ______ and the periphery. Boundary caps maintain separation here as well.
Spinal cord
This axon outgrowth is characterized by an expanded region of cytoplasm with filopodia. It advances via extension/resorption cycles that involve actin microfilaments.
Growth cone
Growth cone outgrowth can depend on the environment it is in. Some influences of the local environment include…
Chemoattraction
Contact attraction
Chemorepulsion
Contact repulsion
Growth cones can respond to concentration gradients of diffusible substances. They can be attractant diffusible substances, i.e. _______, or they can be repulsive diffusible substances, i.e. ________.
Netrins
Semaphorins
Growth cones can also respond to fixed physical or chemical cues from the microenvironment immediately surrounding them. Some of these include…
Caudal half of somite
Fibronectin and laminin
Integrins
Cadherins
In a peripheral nerve, one _________ axon typically precedes the others in growing toward its target. Other axons follow, forming ________ (bundles) of axons.
Pioneering
Fascicles
Fasciculation of axons is facilitated by intercellular adhesion proteins such as ______, which help bind parallel nerve fibers.
L1
_______ is present on the surfaces of most embryonic nerve processes and muscle fibers and is involved in the initiation of neuromuscular contacts.
N-CAM
The cytoskeletal backbone of an axon is an ordered array of ________ and ________.
Microtubules
Neurofilaments
These are long, tubular polymers composed of tubulin subunits.
Microtubules
As an axon extends from its cell body, tubulin subunits are transported down the axon and polymerize onto the distal end of the microtubule. The assembly of ________ is organized in a similar polarized manner.
Neurofilaments
The site of these cytoskeletal additions is close to the base of the growth cone, meaning that the axon elongates (DISTALLY/PROXIMALLY) rather than being pushed out by an addition to its (DISTAL/PROXIMAL) end near the neuronal cell body.
Distally
Proximal
A characteristic accompaniment of axonal growth is the production of large amounts of _______.
GAPs
***Mainly GAP-43
When a motor axon meets a muscle fiber, there is _______ of outgrowth of axon.
Cessation
When a motor axon meets a muscle fiber, there is preparation by the neuron for release of neurotransmitter molecules. Synaptic vesicles fill with ______, and there is induction of synaptic vesicle release sites.
ACh (Acetylcholine)
When a motor axon meets a muscle fiber, the muscle fiber prepares for signal transduction. There is junction-specific ACh receptors that become concentrated in postsynaptic folds. Nonjunctional ACh receptors are eliminated. ________ accumulates in basal lamina.
ACh-esterase
***Study Lecture 16 Slide 42
Sympathetic preganglionic motor neurons arise from _______ _______ of gray matter. Levels of origin are from T1 through L2.
Intermediate (lateral) horns
Myelinated axons move through the ventral roots of the spinal cord and then through the…
White communicating rami
Axons enter sympathetic ______ ganglia or ______ ganglia. Autonomic ganglia are derived from ______ _____ cells.
Chain
Collateral
Neural crest
Preganglionic axons synapse with cells bodies of postsynaptic sympathetic motor neurons within the ganglia. Postganglionic autonomic neurons are derived from ______ ______ cells.
Neural crest
Preganglionic sympathetic fibers have several options –
- Ascend or descend within the sympathetic chain to more anterior (cranial) or more posterior (caudal) ganglia and synapse with postganglionic neurons.
- Synapse immediately with __________ neurons.
- Pass to more peripheral collateral ganglia to synapse with postganglionic neurons.
Postganglionic
Sympathetic postganglionic motor neurons are not ________ and may extend directly from collateral ganglia to target organs.
Myelinated
Sympathetic postganglionic motor neurons may reenter the ventral root of the spinal nerve through…
Gray ramus communicans
Parasympathetic preganglionic motor neurons levels of origin include _______, _______, and _______.
Midbrain
Hindbrain
S2-S4
Parasympathetic preganglionic motor neurons in cranial regions are associated with cranial nerves…
III
VII
IX
X
Parasympathetic preganglionic motor neurons have axons that are typically long and synapse with postganglionic neurons within _______ in or near the walls of the target organs.
Plexuses
The _____ _____ may have considerable influence in the migratory and mitotic activity of parasympathetic preganglionic motor neurons.
Gut wall
______ determine whether migrating neural crest cells differentiate into autonomic neurons or other neural crest derivatives.
BMPs
The shift of determined autonomic neurons into sympathetic or parasympathetic neurons is due to a multitude of _______ _______.
Transcription factors
The shift of determined autonomic neurons into sympathetic or parasympathetic neurons also involves selecting the specific type of neurotransmitter to be used. Sympathetic cells are typically ________ and parasympathetic cells are typically _________.
Adrenergic
Cholinergic
