Dopaminergic Amacrine Cell

References

Most of this page comes from my notes on Dacey (1990) The Dopaminergic Amacrine Cell.

• Postsynaptic connections (Input) Input appears to be via spines on dendrites. Dacey (1990)
  • Cone Bipolars
  • Other Amacrines

• Presynaptic connections (Output) Output appears to be via varicosities on axon-like processes. Dacey (1990)
  • AII

• Function
  • The "off" switch for the AII-mediated rod pathway.

• Morphology
  • Dacey (1990)
    • Soma diameter
      • ~13 um @ 2mm from fovea
      • ~14.6 um @ 16mm from fovea
      • mean 13.5 um
      • stdev 1.1 um
      • range 11.2 - 16.6 um
    • dendritic tree
      • densely spined
      • sparsely branched
      • primary dendrite diameter ~1-2 um
      • radiate in about the same plane as the soma
      • bifurcate close to soma
      • don't curve or wind much, pretty striaght
      • Dendritic field diameter (mature Macaque nemestrina)
        • ~350 @ 2mm from fovea
        • ~500 @ 16mm from fovea
        • mean 510 um
        • stdev 82 um
        • range 299 - 734 um
    • axon-like processes
      • several
      • extremely thin
      • arise from soma and dendrites which are near the soma.
      • longer than 3 mm probably 4-5 mm
      • It appears that these processes form a network of fibers known as the TH immunoreactive plexus.

• Array characteristics
  • Dacey (1990)
    • Axon-like processes have a coverage factor at least 300
    • Dendrites have a coverage factor
      • 500 um diameter * 14cells/mm2 = about 3
      • ".. the shallow density gradient across the retina for the TH-immunoreactive cells is in inverse relationship with the equally small change in dendritic field size...; the result is a roughly constant coverage from central to peripheral retina.
    • Most cells were found at 6mm or greater from the fovea, but nothing is really know about 0-3mm because of technical problems created by optic fiber thickness and cell density. This appears to be off a bit because of technique (HRP-filling).
    • immunoreactive staining provides a better description of cell density: ~10 cells/mm2 in far periphery to ~50 cells/mm2 in central retina.
    • the density decline was radially symmetric.

• Compartmental Model Characteristics

• Location
  • Dacey (1990)
    • Both dendrites and axon-like processes narrowly stratify close to the outer border of the inner plexiform layer.
    • In a few cases an axon-like process projected into the outer nuclear and outer plexiform layers.
    • The dendrites are described as having a mean/SD IPL depth of 81/5%
    • The axons are described as having a mean/SD IPL depth of 83/4%

• Subclasses

• Synapse types

• Synapse Receptors

• Neurotransmitters
  • Releases dopamine

• Immunoreactivity
  • Dacey (1990)
    • acride orange stains
    • tyrosine hydroxylase (TH) immunoreactive

• Nomenclature
  • May be the same cell as the dopaminergic interplexiform cell (in monkey)
  • Dacey (1990)
    • strong evidence that this amacrine is the large TH amacrine cell
    • not the monoamine-accumulating amacrine cell type in the cat's retina

  Back to list of cells

  Back to general retina list

  visit(s) to this page.

  © 1995 Lance Hahn (lance@retina.anatomy.upenn.edu)