NeuroAnatomy - Lecture 14 - Neural Tube Development Flashcards
What is the neural tube?
primitive embryonic tube-like structure that is the precursor to the CNS
What is the process called that develops the neural tube?
Neurulation during first month of embryonic development
How do neural tube defects occur?
when the neural tube fails to close during neurulation in either rostral or caudal neuropores
What are the embyronic stages leading to neural tube development?
Fertilization/Implantation, Gastrulation, Neurulation
What is the time period of fertilization?
0-7 days before implantation
When does implantation occur?
day 7 after fertilization
When does gastrulation occur?
during the week after implantation, and by day 15-16 gastrulation is complete
What are the three primary layers formed in the gastrulation period?
endoderm, mesoderm, ectoderm
What is the Mesoderm?
middle germ layer // circulatory and skeletal systems as well as serous membranes lining body cavities
What is the Endoderm?
internal germ layer // forms lining of the gut and other internal organs
What is the Ectoderm?
external germ layer // forms the skin, brain, nervous system, and other external tissues
When does neural tube development occur?
begins during the third week and closes by the end of the fourth week
What is happening in week 3 of gestation approx. ~17-18 days after fertilization for neural tube development?
approx. ~17-18 days after fertilization, neural plate forms and neural groove is first seen along midline of neural plate
What is happening in week 3 of gestation approx. ~20 days after fertilization for neural tube development?
neural groove begins to thicken, elevate, and fold, eventionally becomes the neural crest
What is happening in week 4 of gestation during neural tube development?
neural folds fuse to form the neural tube // leaves 2 openings at each end that are called neuropores, which eventually fuse a rostral neuropore and caudal neuropore
What is happening at the end of week 4 of gestation in neural tube development?
it is completely fused by day 27
What happens after neurulation is complete for the neural TUBE?
develops into the CNS central canal, represents future development of ventricular system
What happens after neurulation is complete for the neural CREST?
After the neural crest has formed, it goes on to develop into the PNS
What happens after neurulation is complete for the Ectoderm?
continues to develop into mammillary glands, hypophysis, subcutaneous glands, epidermis, hair, skin, nails, tooth enamel
What are types of Neural Tube Defects?
Anencephaly, Encephalocele, Spina Bifida
What is Anencephaly?
parts of the brain and skull fail to develop // failure of anterior or rostral neuropore fail to develop or fuse. not compatible with life. brain does not develop
What is Encephalocele?
failure of skull to fully close, allowing brain and meninges to form a sac and protrude out of the skull // failure of anterior/rostral neuropore fusing. treated with surgery, neurologic defiits will persist w/ multiple surgeries depending on location
What is Spina Bifida?
failure of vertebral column to fully close, allowing spinal cord and meninges to form a sac and protrude out of vertebral column
failure of posterior neuropore to develop and fuse
What are the three types of Spina Bifida?
Spina bifida occulta, meningocele, meningomyelocele
