2 – Neural Development Flashcards
Development of NS marks the creation of:
-the first organ system
>not the first system to be functional
Neurulation:
-process of ectoderm folding to become the CNS
Neural crest develops:
-PNS
Neural tube develops:
-CNS
Neural tissue develops from:
-a small portion of the ectoderm
>notochord (central mesoderm) signals with sonic the hedgehog to ectoderm=differentiation to become neuroectoderm (CNS)
-several layers of ectoderm migrate laterally to form neural crest (PNS)
Neural fold will:
-fuse at midline (dorsally and transversely)
>gives rise to neural tube
Neural tube:
-fuses and extends in a cranial and caudal fashion
Anterior neuropore:
-gives rise to the brain
Posterior neuropore:
-give rise to brain stem and spinal cord
Somites:
-lateral collection of specialized mesoderm (paraxial mesoderm)
-forms bones, muscles, and connective tissue of the vertebral column and rib cage
Failure of neural tube closure due to:
-not enough proper nutrients and vitamins (ex. folic acid)
-viruses
>maternal illness such as diabetes can also affect neural tube development
*failure of neural tube closure results in development abnormalities
What nutrients and vitamins are critical for proper embryogenesis (neural tube closure)?
-many
*folic acid (Vitamin B9) seems to very important in preventing neural tube defects
>supports cell development and division
Common neural tube defects:
-anencephaly
-spinal bifida
-dermoid sinus
-tethered cord syndrome
Anencephaly:
-head of neural tube does not close
-absence of major portion of brain, skull and scalp
Spinal bifida:
-incomplete closing of spine
Dermoid sinus:
-incomplete separation of neural tube (neuroectoderm from ectoderm)
>viruses can get in as there is a direct connection into NS from the skin
Tethered cord syndrome:
-tissue attaches itself to the SC
>limits the movement of the SC
Failure of neural tube closure: Manx cats example
-caudal neural tube defect (incomplete closure)
-results in vary types of detects
-stumpies and rumpies
Vary types of defects in Manx cats include:
-no tail/vertebrae
-no caudal SC
-pelvic limb dysfunction (mild, moderate, severe)
-death
Stumpies vs. rumpies: Manx cats
-stumpies: short tail
-rumpies: no tail
Failure of neural tube closure: Rhodesian Ridgebacks
-incomplete closure of neural tube (dorsally)=dermoid sinus formation
Dermoid sinus formation: Rhodesian Ridgebacks
-ectoderm (skin) is incompletely separate from neuroectoderm (SC)
-various depths are observed