What does the mesoderm become or give rise to?
- Red Blood Cells
- Connective Tissue (e.g. tendons, ligaments, cartilage, etc.)
Spina Bifida with Myeloschisis
The spinal cord can be seen externally since the skin does not cover the protruding defect; causes alpha protein levels to increase.
The process in which the epiblast cells migrate through the primitive streak and into the interior of the bilaminar disk.
It the failure of the neural tube to spontaneously close of the cranial end; this condition is incompatible with life. Causes high alpha fetal protein levels and polyhydramnios during pregnancy.
Which neurpore closes first?
The cranial neuropore closes prior to the caudal neuropore
Where does myelomeningocele occur?
Occurs at lumbar/sacral regions of spine; thus, lower extremity and bowel/bladder issues.
Where do neural crest cells arise from?
As the neural folds fuse, a population of cells separate from the tips of the neural folds to become a mas of mesenchymal cells called the neural crest.
What does the endoderm become or give rise to?
- Gut (digestive tube and associated organs)
What are complications of using shunt?
They can be infected cuasing infeciton the layers of the brain, leading to meningitis and encephalitis; there can be mechanical problems such as clogging.
It is the failure of the neural tube to spontaneously close at the caudal end.
After formation, what do the neural folds do?
They grow towards each other and then fuse at the midline, converting the neural groove into the neural tube
What happens to the hypoblast during invagination?
The hypoblast is displaced by the first invaginating cells until they are completely replaced, forming the endoderm.
Spina Bifida with Meningocele
The meninges protrude through the vertebral defect without protrusion of spinal cord – skin covers.
Spina Bifida with Myelomeningocele
Both the meninge and the spinal cord potrude through the vertebral defect – skin covers; there associations to chiari tube malformations and hydrocephaly and alpha protein levels will be increased.
What does the ectoderm become or give rise to?
- Epidermal Cells of Skin
- Neurons of the Central Nervous System
- Neural Crest Cells, which will form much of the face.
What are the human genes associated with Neural Tube Defects (partial list)?
What are some of the difficulties associated with spina bifida?
Paralysis in lower extremeties
Bowel and bladder function
Curvature of Spine
Where is the bilaminar disk situated?
The bilaminar disk is situated above the blastocoel but below the amniotic cavity.
How is the pressure from hydrocephaly minimized?
The pediatric surgeon would place a shunt tube (silicone) through the back of the head into the water (CSF) cavity and is then connected to the abdomen which can observe the fluid.
Why does hydrocephaly occur in spina bifida with myelomeningocele?
The posterior part of the brain blocks the exit of the cerebrospinal fluid causing it to accumulate near the brain.
What can be said about the genes associated with neural tube defects (NTD) in mice vs. human?
Despite around 250 mouse mutants that give rise to NTDs, a more limited number (~50) have been associated with human NTDs
What is the surgical procedure for the repair of spina bifida?
Mother is opened in the abdomen. The fetus' tissue on the defect is cut open then removed. The spinal cord is freed from surrounding tissue and the protected using the dura (suture method). The muscle layers and skin layers are closed over the defect; if not enough skin is present then a patch is placed over the defect and a secondary one to reinforce – a final skin substitute is placed on top.
Spina Bifida Oculta
Only affects the vertebral arch, leaving spinal chord intact; in spina bifida occulta, there is no increase in alpha fetal protein levels.
After the formation of the neural plate, what occurs?
The edges of the neural plate extend upward to become the neural folds with the forming medial depression becoming the neural groove.
After closure of the cranial neuropore, what structure result?