What is a retraction bulb?
Lesioned CNS axons form characteristic swellings at their tips known as retraction bulbs, which are the nongrowing counterparts of growth cones. Thus, the stability and organization of microtubules define the fate of lesioned axonal stumps to become either advancing growth cones or nongrowing retraction bulbs.
What is primary axotomy?
In primary axotomy, part of the axon is separated from the cell body at the time of injury such that structural continuity is lost through direct application of mechanical force to the axon with axon bulb formation beginning in 30 minutes.
What is peripheral axotomy?
An axotomy is the cutting or otherwise severing of an axon. In mature animals, where survival factors are derived locally or via autocrine loops, axotomy of peripheral neurons and motoneurons can lead to a robust regenerative response without any neuronal death.
What causes Chromatolysis?
Chromatolysis is the dissolution of the Nissl bodies in the cell body of a neuron. It is an induced response of the cell usually triggered by axotomy, ischemia, toxicity to the cell, cell exhaustion, virus infections, and hibernation in lower vertebrates.
Is astrocyte in CNS or PNS?
Neuroglia in the CNS include astrocytes, microglial cells, ependymal cells and oligodendrocytes. Neuroglia in the PNS include Schwann cells and satellite cells. Astrocytes support and brace the neurons and anchor them to their nutrient supply lines.
What do astrocytes do in CNS?
Astrocytes are the most numerous cell type within the central nervous system (CNS) and perform a variety of tasks, from axon guidance and synaptic support, to the control of the blood brain barrier and blood flow.
What is the end of an axon called?
axon terminal
The end branches of an axon are called telodendria. The swollen end of a telodendron is known as the axon terminal which joins the dendron or cell body of another neuron forming a synaptic connection.
What are axon terminals?
aka axon terminals, synaptic boutons are small swellings that are found at the terminal ends of axons. They are typically the sites where synapses with other neurons are found, and neurotransmitters are stored there to communicate with other neurons via these synapses.
What is posterior root ganglion?
Anatomical terminology. A dorsal root ganglion (or spinal ganglion; also known as a posterior root ganglion) is a cluster of neurons (a ganglion) in a dorsal root of a spinal nerve. The cell bodies of sensory neurons known as first-order neurons are located in the dorsal root ganglia.
What happens when an axon is severed?
Scientists do know that a severed axon will cause a neuron to quickly lose some of its incoming connections from other neurons. These connections occur at short, root-like tendrils called dendrites, which sprout from the neuron’s cell body, or soma.