FRQ

• What is the neurovascular unit in the eye?

  Collection of various cell types such as:

  • Glial cell activity
• What happens to the cells of the neurovascular unit in diabetic retinopathy?


  High blood glucose levels lead to improper glycation of proteins, lipids, and DNA.

  1. Pericytes do not receive PDGF-BB
  2. Endothelial cells rely on pericyte survival so they do not survive
  3. Loss of tight junctions that maintain the BBB and toxins enter the eye
  4. Fluids can leak out of the eye and lead to macular edema
  5. Oxygen deprivation and lead to inflammatory processes and cell death
  6. Astrocytes (glial cells) are activated and release VEGF
  7. VEGF leads to growth of new vasculature in the eye but can still lead to death
• What are the stages of diabetic retinopathy?

  There are four stages:

  1. Mild nonproliferative retinopathy
  2. Moderate nonproliferative retinopathy
  3. Severe nonproliferative retinopathy
  4. Proliferative diabetic retinopathy
• What characterizes mild nonproliferative retinopathy?

  First stage of diabetic retinopathy that occurs at the beginning stages of pericyte and endothelial cell loss
• What characterizes moderate nonproliferative retinopathy?

  Second stage of diabetic retinopathy in which hemorrhages ischemia and macular edema begin to occur
• What characterizes severe nonproliferative retinopathy?

  Third stage of diabetic retinopathy is due to high levels of inflammation and ischemia while lacking neovascularization
• What characterizes proliferative retinopathy?

  The final stage of diabetic retinopathy is due to the formation of new vasculature in the eye causing macular edema. Significant vision loss.
• What are the cranial meninges?

  There are three layers:

  • Dura mater
  • Inner: meningeal layer
  • Outer: endosteal layer
  • Arachnoid mater
  • Pia mater
• In what part of the meninges does blood flow?

  Blood flows across the subarachnoid space
• What is the neurovascular unit in the eye?

  Inner retinal barrier

  1. Neuronal cells
  2. Cells that make up vasculature
  3. Pericytes
  4. Endocytes
  5. Processes from glial cells
  6. Retinal astrocytes
  7. Microglial cells
  8. Muller glia
• Where are lymphatic vessels that service the central nervous system?

  Lymph vessels along blood vessels in the superior sagittal and transverse sinuses of the dura
• Where to lymphatic vessels that service the CNS drain?

  Into the cervical lymph nodes
• What are the two pathways by which neural crest cells migrate?

  Dorsolateral and ventral
• Discuss 5 cell types that are generated from the neural crest?

  Five types includes:

  • Melanocytes in skin, hair follicles, iris
  • DRG (neurons, satellite cells, Schwaan cells)
  • Malleus, Incus, Stapes in the ear
  • Sympathetic ganglion neurons (not in spinal cord)
  • Tooth primordia (dentine)
• Neurofibromatosis, Type 1

  Mutations in NF1, a tumor suppressor
• Waardenburg Syndrome

  Mutations in Pax3 or Mitf gene causing melanocyte defects on the head
• DiGeorge Syndrome

  Mutations in the Tbx1 causes heart and craniofacial defects
• Melanoma

  Mutations of CDKN2A leads to destabilization of P53 leading to cancer