Question 1

A child is diagnosed with congenital insensitivity to pain with anhidrosis.The receptor for which growth factor is mutated in this condition?&#10;A) Epidermal growth factor&#10;B) Transforming growth factor beta&#10;C) Scatter factor&#10;D) Fibroblast growth factor&#10;E) Nerve growth factor

Accepted Answer

Congenital insensitivity to pain with anhidrosis is a disorder caused by mutations in the gene that encodes nerve growth factor (NGF) receptor, also known as tyrosine kinase A (TrkA) receptor. NGF induces the differentiation and survival of neurons and plays a crucial role in the development of the sensory and sympathetic nervous systems. Mutations in TrkA receptor impair the function of sensory and sympathetic neurons, leading to the inability to feel pain and the inability to sweat. Therefore, choice E (nerve growth factor) is the best answer.

Question 2

Hereditary peripheral neuropathies,such as Charcot-Marie-Tooth hereditary neuropathy,involve nerve demyelination.What cell type myelinates peripheral nerves during development?&#10;A) Schwann cells&#10;B) Oligodendrocytes&#10;C) Astrocytes&#10;D) Chromaffin cells&#10;E) Endothelial cells

Accepted Answer

Schwann cells are the cell type responsible for myelinating peripheral nerves during development. They form a one-to-one relationship with axons, producing myelin to insulate and enhance nerve signal transmission. In hereditary peripheral neuropathies such as Charcot-Marie-Tooth hereditary neuropathy, Schwann cells fail to properly maintain or form myelin sheaths, causing demyelination and subsequent nerve dysfunction.

Question 3

Neurogenesis in the PNS involves both positive and negative regulators.Which signaling pathway plays an essential role as a negative regulator of neurogenesis?&#10;A) Tyrosine kinase&#10;B) Tgfbeta&#10;C) Integrin&#10;D) Ephrin-Eph&#10;E) Notch-Delta

Accepted Answer

The Notch-Delta signaling pathway plays an essential role as a negative regulator of neurogenesis in the PNS. Activation of the Notch receptor by Delta ligands expressed on neighboring cells leads to the inhibition of neurogenesis by preventing the differentiation of neural progenitor cells into neurons. This pathway is a well-known negative regulator of neurogenesis in both the PNS and the CNS.

Question 4

A researcher labels the second epibranchial placodes.Cells of what structure(s)will be labeled later in development?&#10;A) Olfactory nerve&#10;B) Vestibulocochlear nerve&#10;C) Superior ganglion&#10;D) Petrosal ganglion&#10;E) Enteric ganglia

Accepted Answer

The answer of A researcher labels the second epibranchial placodes.Cells...

Question 5

A patient is diagnosed with neurofibromatosis type 1.What type of gene is mutated in this condition?&#10;A) Transcription factor&#10;B) Growth factor&#10;C) Extracellular adhesion molecule&#10;D) Tumor suppressor gene&#10;E) Cytoskeletal protein

Accepted Answer

Neurofibromatosis type 1 is caused by mutations in the tumor suppressor gene NF1, which encodes for neurofibromin.

Deck 11: Development of the Peripheral Nervous System