Neurulation & Neural Crest Flashcards
gastrulation
the formation of the 3 primary germ layers
3 parts of the primitive streak
primitive knot
primitive groove
primitive pit
the neural plate will form the ______ by releasing ____
central nervous system
sonic hedgehog
somites
come from the paraxial mesoderm
- form the myotome, sclerotome, and dermatome
intermediate mesoderm becomes the
urogenital system including kidneys and gonads, ducts, and accessory glands
lateral plate mesoderm becomes ____
connective tissue
- blood
- lymph
- mesenteries
- cardiovascular
surface ectoderm becomes
hair, skin, nails, mammary glands, teeth enamel, internal ear, lens of eye
primary neurulation
the neural plate folds in and closes; the closing of the rostral neuropore
- occurs at around day 25
- closure of brain, cervical, thoracic, and lumbar portions of spinal cord
secondary neurulation
caudal eminence fuses with posterior neuropore to form the sacral and coccyx part of the spinal cord
- hollow tube is formed
neural crest cells
found in the cranial and trunk regions; give rise to sensory neurons only
- spinal ganglia
- autonomic ganglia
- cranial nerves 5, 7, 9, 10
neurilemma
supporting cells arising from the neural crest; the schwann cels; they myelinate the neurons in the peripheral nervous system
leptomeninges
supporting cells arising from the neural crest; the pia and dura mater
ectomesenchyme
arises from neural crest
- bone and cartilage of facial skeleton
- walls of large arteries from aortic arches
- enamel and dentin
Hirschsprung’s disease
type of trunk neural crest defect; megacolon - autonomic system does not innervate the colon so infants cannot defecate
aorticopulmonary septation defects of the heart can be caused by what neural crest defect
cranial
cleft lip and/or cleft palate can be caused by what neural crest defect
cranial
DiGeorge syndrome
type of cranial neural crest defect
- hypoparathyroidism, thyroid deficiency, thymic dysplasia leading to immunodeficiency, defects in cardiac outflow tract and aortic arches
dental anomalies can be caused by what neural crest defect
cranial
neuroblastoma
- what is it
- what neural crest defect causes it
tumor of adrenal medulla and/or autonomic ganglia
proliferation defects
what embryological event can cause albinism
neural crest defect
alpha fetal protein
shown to be increased in cases of meningocele, meningomyelocele, and myelocele; indicative of neural tube defects
- can use amniocentesis to test for this
what supplement can prevent neural tube defects
folic acid
spina bifida occulta
caused by the caudal neural pore not closing properly; results in a gap between spinous processes and sometimes a tuft of hair on the lower back and/or a dimple
- patients are normal
meningocele
caudal neural pore closed but there are not vertebral arches or neural arches; causes a CSF filled cyst on the meninges that can be surgically repaired; spinal cord is NOT located in the cyst
meningomyelocele
caudal neural pore closure defect; patients have a cyst on the spinal cord that DOES contain the meninges and spinal cord
- sensory and motor defects
myelocele
caudal neural pore did not close and the spinal cord is exposed; surgically corrected after birth; motor and sensory defects
Anencephaly
patients are missing the bony covering of the skull and part of the brain; incompatible with life; brain stem is intact and there is normal respiratory and cardiac function
- patients at risk for infection
encephalocele (with brain tissue)
neural tube defect characterized by sac-like protrusions of the brain and the membranes that cover it through openings in the skull; defects are caused by failure of the neural tube to close completely during fetal development.
- mental and physical deficits
encephalocele (without brain tissue)
neural tube defect with sac-like protrusions that do NOT contain brain material and the patients are usually normal; caused by failure of the neural tube to close completely in development
when is the rostral tube closure finished
day 28
what do the meninges develop from
meninx primitiva
meninx primitiva
mesoderm in origin; derived from sclerotome; contains some neural crest cells that have migrated in
- divides into pachymenix and leptomeninges
pachymeninx
the dura mater; derived from mesoderm portion of the meninx primitiva
leptomeninges
the arachnoid and pia mater; derived from the neural crest cells of the meninx primitiva
the meninx primitiva divides into two cell populations called:
pachymeninx (dura mater)
leptomeninges (arachnoid and pia mater)
paraxial mesoderm forms:
muscles of head, striated skeletal muscle (trunk, limbs), skeleton except cranium, dermis of skin, connective tissue
lateral mesoderm forms:
connective tissue and muscle of viscera, primordial heart, spleen, blood and lymphatic cells, adrenal cortex
neuroectoderm forms what two main branches
neural crest and neural tube
neural crest forms
- cranial and sensory ganglia and nerves
- medulla of suprarenal gland
- pigment cells
- pharyngeal arch of cartilages
- head mesenchyme and connective tissue
- bulbar and conal ridges in heart
neural tube forms
- central nervous system
- retina
- pineal body
- posterior part of pituitary gland
Endoderm from the trilaminar embryonic disc forms
- Epithelial parts of (pharynx, thyroid gland, tympanic cavity, pharyngotympanic tube, so tilts, parathyroid glands)
- epithelium of (GI tract, liver, pancreas, urinary bladder, urachus)
- epithelial parts of (trachea, bronchi, lungs)
When are the upper limb bud, lower limb bud, primordial of lens, and the fourth pharyngeal arch formed by
Week 4
