A new look at calretinin-immunoreactive amacrine cell types in the monkey retina

J Comp Neurol. 2002 Nov 11;453(2):168-84. doi: 10.1002/cne.10405.


We have examined amacrine cells that are calretinin-immunoreactive (-IR) in the macaque monkey retina with the aim of classifying them into morphological and functional subtypes. There are calretinin-IR cells in the fovea and throughout the retina. Their highest density is reached at 1.0 mm from the foveal pit (10500 cells/mm(2)) and falls to 2600/mm(2) by 10 mm of eccentricity. Nearest-neighbor statistics for the calretinin-IR cell body distribution indicate a nonregular pattern, with a regularity index of 1.4-1.6. There is an increase or "bump" of cell density 3.5-4.0 mm from the foveal pit, corresponding to the rod photoreceptor density peak. Based on morphological differences, there appear to be three types of amacrine cell that are calretinin-IR. To determine the types, we doubly immunolabeled retinas, from fovea to periphery, for calretinin-IR in combination with other calcium binding proteins and inhibitory amino acid neurotransmitters. Labeling with parvalbumin and calretinin antibodies indicated that 70% of the amacrine cells were solely calretinin-IR, and 30% contained parvalbumin-IR as well. In the same way, 70% of the calretinin-IR amacrine cells colocalized calbindin, but 30% were only calretinin-IR. Among the calretinin/calbindin-colocalized cells, there were small-field and wide-field types. Double labeling with antibodies to calretinin and gamma-aminobutyric acid (GABA) and to calretinin and glycine revealed the majority to be glycine-IR, but some were GABA-IR. The glycine-IR population consists mainly of AII amacrine cell types, but clearly another non-AII type is involved. The non-AII glycine-IR population resembles a small- to medium-field diffuse type. The calretinin-IR wide-field type is GABAergic and corresponds to an A19 type. The central, rod-free, fovea contains the calretinin-IR, non-AII glycine-IR type and the calretinin-IR, GABAergic type only. To learn more concerning the circuitry of the calretinin/glycine-IR, non-AII amacrine cell type in isolation from AII amacrine cells, we concentrated on the rod-free fovea, where AII amacrine cells are absent. We performed a serial section electron microscopy (EM) study on four calretinin-IR cells. They were involved with cone pathway circuitry. They got input from ON and OFF midget bipolar cells, reciprocated synapses to these bipolar cells, and provided synapses to ON-center ganglion cells. Thus we have obtained new information on a cone pathway amacrine cell of the central monkey fovea that is involved in the midget system.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amacrine Cells / chemistry*
  • Amacrine Cells / ultrastructure*
  • Animals
  • Antibodies
  • Calbindin 2
  • Calbindins
  • Cell Count
  • Cell Size
  • Fovea Centralis / cytology
  • Glycine / analysis
  • Glycine / immunology
  • Macaca mulatta / anatomy & histology*
  • Microscopy, Electron
  • Parvalbumins / analysis
  • Parvalbumins / immunology
  • S100 Calcium Binding Protein G / analysis*
  • S100 Calcium Binding Protein G / immunology
  • Synapses / chemistry
  • Synapses / ultrastructure
  • gamma-Aminobutyric Acid / analysis
  • gamma-Aminobutyric Acid / immunology


  • Antibodies
  • Calbindin 2
  • Calbindins
  • Parvalbumins
  • S100 Calcium Binding Protein G
  • gamma-Aminobutyric Acid
  • Glycine