OTD 341 Exam 1 - Neurodevelopment

false

True or false: the nervous system is completely developed at birth.

3rd week

In what week of embryonic development do chemical signals lead to the formation of the neural plate?

ectoderm

The neural plate is a thickened portion of which germ layer? (ectoderm, mesoderm, endoderm)

ectoderm

What germ layer gives rise to the nervous system? (ectoderm, mesoderm, endoderm)

neural plate

What embryonic structure is formed during the 3rd week of embryonic development due to chemical signaling?

neural plate

• thickened portion of the ectoderm that forms during the 3rd week of embryonic development following chemical signaling

• folds inward to form the neural groove in the midline with neural folds on each side

neural groove, neural folds

After the formation of the neural plate (a thickened portion of ectoderm) in the 3rd week of embryonic development, the neural plate folds inward to form the _____ ______ in the midline with ______ ______ on each side.

beginning of 4th week

When do the neural folds fuse in the midline to form the neural tube?

end of 4th week

In typical embryonic development, when is the entire neural tube closed?

primary neurulation

• neural plate forms following chemical signaling during the 3rd week

• neural plate folds inward to form the neural groove in the midline with neural folds on each side

• neural folds begin to fuse midway along the neural groove to form the neural tube by the beginning of the 4th week

• entire neural tube is close by the end of the 4th week

• neural tube separates from the ectoderm, leaving neural crest cells, which eventually give rise to most of the PNS

• also during the 4th week, the sulcus limitans appears as a longitudinal groove in the wall of the neural tube that separates the neural tube into dorsal (alar plate; sensory functions) and ventral (basal plate; motor functions) halves

• 3 primary vesicles also appear in the neural tube during the 4th week

neural crest cells

• cells that originate from the crest of neural folds that give rise of a variety of cell types, including much of the peripheral nervous system: dorsal root ganglia (sensory neurons), autonomic ganglia, adrenal medulla, some cranial nerves, etc.

• separate from neural folds as neural folds fuse, forming the neural tube and simultaneously separating from the ectoderm

ventricular system of the brain, central canal of the spinal cord

The cavity of the neural tube developes into almost the entire CNS; its cavity becomes the ______ ______ ____ ___ _____ and the _____ _____ ____ ____ ____ ____.

CNS

The neural tube gives rise to what division of the nervous system? (CNS or PNS)

PNS

The neural crest cells give rise to what division of the nervous system? (CNS or PNS)

secondary neurulation

Following the closure of the neural tube, a secondary cavity forms into cells caudally during the 5th and 6th weeks, forming the sacral spinal cord region

5th and 6th weeks

During which weeks of embryonic development does secondary neurulation occur?

sacral

Secondary neurulation is the process by which a secondary cavity forms into cells caudally during the 5th and 6th weeks of development, forming the ______ spinal cord region.

4th week

During what week of development does the sulcus limitans appear?

sulcus limitans

• longitudinal groove that appears in the wall of the neural tube in the 4th week

• separates neural tube, and eventually brain and spinal cord, into a dorsal half and ventral half

• dorsal: alar plate, sensory functions

• ventral: basal plate, motor functions

dorsal, ventral

The sulcus limitans, which is a longitudinal groove in the wall of the neural tube that appears during the 4th week of development, separates the neural tube, and eventually the brain and spinal cord, into _____ and _____ halves.

alar, sensory

Dorsal to the sulcus limitans (which is a longitudinal groove in the wall of the neural tube that appears during the 4th week of development) is the _____ plate which is associated with _____ functions.

basal, motor

Ventral to the sulcus limitans (which is a longitudinal groove in the wall of the neural tube that appears during the 4th week of development) is the _____ plate which is associated with _____ functions.

ventral, motor

The basal plate is ____ to the sulcus limitans (which is a longitudinal groove in the wall of the neural tube that appears during the 4th week of development) and is associated with ____ functions.

dorsal, sensory

The alar plate is ____ to the sulcus limitans (which is a longitudinal groove in the wall of the neural tube that appears during the 4th week of development) and is associated with ____ functions.

basal plate, motor functions, ventral neural tube, anterior spinal cord

When considering the sulcus limitans, what does BMVA mean?

alar plate, sensory functions, dorsal neural tube, posterior spinal cord

When considering the sulcus limitans, what does ASDP mean?

4th week

During what week of development do the 3 primary vesicles appear?

3

How many primary vesicles are there?

prosencephalon, mesencephalon, rhombencephalon

What are the 3 primary vesicles?

5

How many secondary vesicles are there?

cephalic flexure, cervical flexure

What are the 2 bends in the neural tube that appear when the 3 primary vesicles emerge during the 4th week?

5th week

During what week of development do the 5 secondary vesicles appear?

telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon

What are the 5 secondary vesicles?

prosencephalon

The telencephalon and diencephalon arise from which primary vesicle?

mesencephalon

The mesencephalon arises from which primary vesicle?

rhombencephalon

The metencephalon and myelencephalon arise from which primary vesicle?

telencephalon, diencephalon

The prosencephalon gives rise to which 2 secondary vesicles?

mesencephalon

The mesencephalon gives rise to which secondary vesicle?

metencephalon, myelencephalon

The rhombencephalon gives rise to which 2 secondary vesicles?

telencephalon

Which secondary vesicle gives rise to the cerebral hemispheres and lateral ventricles?

diencephalon

Which secondary vesicle gives rise to the thalamus, hypothalamus, retina, and third ventricle?

mesencephalon

Which secondary vesicle gives rise to the midbrain and cerebral aqueduct?

metencephalon

Which secondary vesicle gives rise to the pons, cerebellum, and part of the fourth ventricle?

myelencephalon

Which secondary vesicle gives rise to the medulla, part of the fourth ventricle, and central canal?

telencephalon

Which secondary vesicle gives rise to the cerebral hemispheres?

telencephalon

Which secondary vesicle gives rise to the lateral ventricles?

diencephalon

Which secondary vesicle gives rise to the thalamus?

diencephalon

Which secondary vesicle gives rise to the hypothalamus?

diencephalon

Which secondary vesicle gives rise to the retina?

diencephalon

Which secondary vesicle gives rise to the third ventricle?

diencephalon

Which secondary vesicle gives rise to the thalamus, hypothalamus, and retina, among other structures?

mesencephalon

Which secondary vesicle gives rise to the midbrain?

mesencephalon

Which secondary vesicle gives rise to the cerebral aqueduct

metencephalon

Which secondary vesicle gives rise to the pons?

metencephalon

Which secondary vesicle gives rise to the cerebellum?

metencephalon

Which secondary vesicle gives rise to the pons and cerebellum?

metencephalon

Which secondary vesicle gives rise to part of the fourth ventricle?

myelencephalon

Which secondary vesicle gives rise to the medulla?

myelencephalon

Which secondary vesicle gives rise to part of the fourth ventricle and central canal?

myelencephalon

Which secondary vesicle gives rise to the central canal?

metencephalon, myelencephalon

Which 2 secondary vesicles give rise to the fourth ventricle?

cerebral hemispheres

What is the neural derivative of the telencephalon?

thalamus, hypothalamus, retina

What are the neural derivatives of the diencephalon?

midbrain

What are the neural derivatives of the mesencephalon?

pons, cerebellum

What are the neural derivatives of the metencephalon?

medulla

What are the neural derivatives of the myelencephalon?

lateral ventricles

What are the cavities associated with the telencephalon?

third ventricle

What is the cavity associated with the diencephalon?

cerebral aqueduct

What is the cavity associated with the mesencephalon

fourth ventricle

What is the cavity associated with the metencephalon?

fourth ventricle, central canal

What are the cavities associated with the myelencephalon?

cervical flexure

bend between the myelencephalon (future brainstem) and future spinal cord; straightens later in development

cephalic flexure

bend between mesencephalon (future midbrain) and diencephalon; persists into adulthood; reason for “the bend” in the neural axis

pontine flexure

bend between metencephalon (future pons) and myelencephalon (future medulla); does not persist but affects caudal brainstem

pontine flexure

What additional bend appears when the primary vesicles develop into secondary vesicles in the 5th week?

cephalic flexure

Of the 3 bends that appear with the development of the primary and secondary vesicles, what is the only one to persist into adulthood? (cephalic flexure, pontine flexure, cervical flexure)

sensory, motor

Due to the pontine flexure’s flattening of the neural tube at the level of the future pons and medulla, the alar plate is pushed laterally and the basal plate is pushed medially. Therefore, in the future pons and medulla, _____ neurons are lateral to the medial ____ neurons.

pons, medulla

Due to the pontine flexure, sensory neurons are lateral to the medial motor neurons in the future ______ and ________.

lateral, medial

Due to the pontine flexure, sensory neurons are ______ to the _____ motor neurons in the future pons and medulla.

True

True or false: myelination occurs mostly postnatally.

15%

About what percentage of known pregnancies end in miscarriage?

12

About 15% of all known pregnancies end in miscarriage, usually in the first ____ weeks, due to a major anomaly in the formation of the structures of the embryo.

craniorachischisis

complete failure of neural tube to close; incompatible with life

spina bifida

partial failure of neural tube to close; different types range from mild to severe

spina bifida occulta, meningocele, myelomeningocele

Name 3 types of spina bifida discussed in lecture.

spina bifida occulta

type of spina bifida in which there is atypical formation of vertebral column only

meningocele

form of spina bifida in which there is herniation of meninges only

myelomeningocele

form of spina bifida in which there is herniation of spinal cord and meninges

anencephaly

failure of rostral end of neural tube to close resulting in absent cerebral hemispheres; incompatible with life

folic acid

Neural tube closure is dependent on adequate _____ _____ in mother’s diet.

holoprosencephaly

partial or complete failure of prosencephalon to separate into diencephalon and telencephalon; usually fatal, but milder forms are compatible with life

56

At what day in development does an embryo become a fetus?

8

At week in development does an embryo become a fetus?

fetal alcohol spectrum disorder (FASD)

most common cause of intellectual disabilities and the leading preventable cause of congenital malformations in the U.S.

pontine flexure

At which bend in the neural tube does the location of the sensory pathways migrate more laterally and the location of the motor pathways migrate more medially?

spina bifida, anencephaly

Only partial closure of the neural tube results in which diagnosis or diagnoses?

caudal

Spinal bifida is failure of the ____ end of the neural tube to close. (rostral or caudal)

rostral

Anencephaly is failure of the _____ of the neural tube to close. (rostral or caudal)

primary neurulation

The zipping up for the neural tube starting from the center outward and completely closing by the end of week four is known as what?