Neurulation

Question 1

The notochord is from what germ layer?

Answer 1

Mesoderm

Question 2

The notochord is at the midline, and extends from the primitive node (knot) and moves anterior to the prechordal plate. It also acts as the template for the vertebral column, contributing to the ______ _______, and induces the neural plate, which will form the _______.

Answer 2

Intervertebral discs

CNS

Question 3

T/F. The notochord is from mesoderm and induces the neural plate, so that means the neural plate is also from mesoderm.

Answer 3

False. The neural plate is an ectodermal structure.

Question 4

Once then notochord has formed, it will start signaling _______ which will cause the thickening of the cells above it forming the neural plate.

Answer 4

SHH

Question 5

What happens to the neural plate as it invaginates?

Answer 5

Brings the neural folds together with the neural groove in the center.

Question 6

What is on the outer edges of the neural plate?

Answer 6

Neural crest

***As Neural Plate invaginate, the Neural Crest migrates away from it

Question 7

What is the final result of the neural plate invagination?

Answer 7

Formation of the Neural Tube, which develops the CNS (brain and spinal cord)

Question 8

Neural crest cells came from (MESODERM/ECTODERM) but act like (MESODERM/ECTODERM).

Answer 8

Ectoderm
Mesoderm

***Hence why we use purple color, mixing ectoderm (blue) with mesoderm (red)

Question 9

What is the hollow center of the Neural Tube called?

Answer 9

Neural Canal

Question 10

After the neural tube has been formed, we now have two distinct ectoderms. These are…

Answer 10

Surface ectoderm – gives rise to hair, skin, nails, etc.
Neuroectoderm – give rise to CNS (neural tube)

***Also have to say if something was derived from the neural crest (because it’s from ectoderm, but are their own tissue type) – can’t just say ectoderm!

Question 11

As the neural folds invaginate with the neural groove, they zipper shut in what directions?

Answer 11

Rostral (Cranial) and Caudal directions both

Question 12

As the neural tube forms, it leaves openings at either end which are called…

Answer 12

Rostral (Cranial) neuropore
Caudal neuropore

***At the end, the whole thing is zippered up and the openings are closed

Question 13

What day does the Rostral Neuropore close? The Caudal Neuropore?

Answer 13

Day 25

Day 28

Question 14

(PRIMARY/SECONDARY) Neurulation is the formation of the brain to the lumbar region of the spinal cord.

Answer 14

Primary

Question 15

(PRIMARY/SECONDARY) Neurulation is the formation of the sacrum and coccyx.

Answer 15

Secondary

Question 16

What is the region of Secondary Neurulation called?

Answer 16

Caudal Eminence

***Not called this once it is attached to components of primary neurulation – at that point it is just spinal cord

Question 17

What day does Secondary Neurulation begin? What day does it end (when it connects with components of primary neurulation)?

Answer 17

Starts Day 20

Ends Day 42

Question 18

List some of the neuronal cells that come from Neural Crest.

Answer 18

Spinal Ganglia
Autonomic Ganglia
Sensory Neurons

Question 19

List some of the supporting cell types that come from Neural Crest.

Answer 19

Schwann Cells (myelinate in the PNS) 
Cells of Meninges (Arachnoid and Pia Mater)

Question 20

These pigment cells come from the Neural Crest.

Answer 20

Melanocytes

Question 21

These endocrine cells come from the Neural Crest.

Answer 21

C-cells of Thyroid Gland

Chromaffin cells of suprarenal medulla

Question 22

List the ectomesenchyme tissues developed from Neural Crest.

Answer 22

• • Bone and cartilage of facial and visceral skeleton
• • Walls of large arteries from aortic arches
• • Ciliary muscles (eye)
• • Enamel and dentin (teeth)

Question 23

This is a disease of the neural crest because the autonomics of the intestines do not migrate there, causing obstruction. Patient can’t defecate.

Answer 23

Hirschsprung’s Disease

Question 24

What are some Neurocristopathies that can occur in the cranial Neural Crest?

Answer 24

• • Aorticopulmonary septation defects of heart
• • Anterior chamber defects of eye
• • Cleft lip and/or cleft palate
• • DiGeorge Syndrome

Question 25

This is a neurocristopathy derived from cranial neural crest. It presents with hypoparathyroidism, thyroid deficiency, thymic dysplasia leading to immunodeficiency, and defects in cardiac outflow tract and aortic arches.

Answer 25

DiGeorge Syndrome

Question 26

This neurocristopathy can occur due to Neural Crest, which is caused by a melanocyte deficiency.

Answer 26

Albinism

Question 27

Spina bifida occurs when there is a failure of the (ROSTRAL/CAUDAL) neuropore to close.

Answer 27

Caudal

Question 28

In this type of spina bifida, patients appear normal and don't usually have any defects or issues. Occurs in 10 percent of the population. The vertebral arches formed but did not fuse together and there is a tuft of hair on the lower back.

Answer 28

Spina bifida occulta

Question 29

This type of spina bifida occurs when the meninges are herniating into a cyst on the lower back. Patients may or may not have deficits and the vertebral arches did not form.

Answer 29

Meningocele

Question 30

This type of spina bifida occurs when the meninges and the spinal cord are herniated out into a cyst on the lower back. The patient will have motor and sensory deficits and the vertebral arches did not form.

Answer 30

Meningomyelocele

Question 31

This type of spina bifida occurs when the caudal neuropore does not fuse at all, the meninges and spinal cord are open to the environment. The patient will have motor and sensory deficits and the vertebral arches did not form.

Answer 31

Myelocele (myeloschisis)

Question 32

What can be taken to prevent spina bifida?

Answer 32

Folic acid (folate)

Question 33

This is what is present in amniotic fluid that signifies the presence of spina bifida or anencephaly. High levels of it means there could be either of these defects.

Answer 33

Alpha-Fetoprotein

Question 34

In this congenital neural tube defect, the rostral neuropore doesn't close at all and the brain barely forms. Usually not compatible with life.

Answer 34

Anencephaly

Question 35

In this congenital neural tube defect, the rostral neuropore failed to close causing a cyst to form on the back of the head and will or will not have brain tissue inside of it as well.

Answer 35

Encephalocele (with or without brain tissue)

Question 36

This is what gives rise to the meninges.

Answer 36

Meninx Primitiva

Question 37

What germ layer is the Meninx Primitiva made of?

Answer 37

Mesoderm in origin but Neural Crest cells come to populate it as well.

Question 38

This is what develops the dura mater (mesoderm), but has just recently been thought to also get help from Neural Crest.

Answer 38

Pachymeninx

Question 39

This is what develops the arachnoid and pia mater with Neural Crest.

Answer 39

Leptomeninges

Question 40

This is the term for embryonic connective tissue that includes both mesoderm and Neural Crest.

Answer 40

Mesenchyme

Question 41

What occurs during the fourth week of development?

Answer 41

Folding of the embryo