Congenital Disease Associated with Central Nervous system Flashcards
What is Neurulation and at what stage will it occur ?
Neurulation = the process of neural tube formation, occurs at around week 3/4
What does the neural tube form ?
The brain, spinal cord, meninges (membranous covering of brain and spinal cord) and bones that surround them.
cranial nerves, spinal nerves, neural crest, eyes, other sensory organs
What are the three layers of the embryo ?
3 primary germ layers:
Ectoderm
Mesoderm
Endoderm
What is Gastrulation?
Gastrulation is the process during embryonic development that changes the embryo from a blastula with a single layer of cells to a gastrula containing multiple layers of cells.
Gastrulation = the 3 primary germ layers form + start becoming diff. tissue types
occurs in week 3 of development
What does the Ectoderm differentiate into?
This will form the outer component’s of the body e.g.:
Skin
Hair
Nervous system
Mammary glands
What does the Mesoderm differentiate into ?
This will give rise to :
skeletal muscles
smooth muscle
blood vessels
bone
cartilage
joints
connective tissue
endocrine glands
Kidney cortex
Heart muscle
urogenital organ
uterus
fallopian tube
What does the Endoderm differentiate into ?
The pharynx
Oesophagus
Stomach
Small intestine
Colon
Liver
Pancreas
Bladder
Trachea
Bronchi
Lungs
Thyroid
Parathyroid
lines GIT + airways
What is the notochord
The Notochord induces neurulation and will later form the nucleus pulposus
(soft gelatinous central portion of the intervertebral disk )
What is the somite ?
Somites are a set of bilaterally paired blocks of paraxial mesoderm that form the vertebrae, ribs and dermis of the dorsal skin, skeletal muscles of the back and the skeletal muscles of the body wall and limbs.
Describe process of Neurulation
By the end of week3 :
The lateral edges of the ectoderm will become more elevated and form the neural fold.
The depressed mid region = the neural groove. The whole layer = the neural plate (of the ectoderm).
Neurulation will advance both cranially (brain/head) and caudally (tail/spinal chord). It starts from mid-region.
The neural plate will form neural folds on either end, forming the depression in the middle = the neural groove.
How does the neural tube form ?
The outer parts of the neural fold will fuse together forming the neural tube.
The outer section of the ectoderm will move and surround the endoderm and mesoderm.
Describe how the neural crest will form and what’s the function of this structure ?
Week 4
Some of the ectodermal cells will migrate forming several layers of cells called the neural crest.
This will give rise to structures that work closely with the nervous system
E.g- Peripheral nervous system spinal nerves, cranial nerves, ganglia
Autonomic nervous system ganglia
Meninges
What are the different sections of the neural tubes ?
- Prosencephalon - Cerebrum and thalamus
- Mesencephalon - Mid brain
- Rhombencephalon - Pons cerebellum and medulla
- Spinal chord - Spine
What is an Anencephaly
Anencephaly:
Birth defect in which a baby is born without parts of the brain / skull.
Neural tube defect.
Opening is in anterior region
What is Craniorachischisis?
Neural tube defect - neural tube fails to close
Entire spinal cord and brain are exposed.
What is spina bifida ?
Spina bifida:
A birth defect (NTD) that occurs when the spine and spinal cord do not form properly
Opening at the caudal region of neural tube