Abstract
Purpose :
The transcription factor Special AT-rich Sequence Binding Protein 1 (SATB1) has been shown to be expressed by ON-OFF direction-selective (DS) ganglion cells in the mouse retina (Peng et al. ,2017, Neuron). The purpose of this study was to identify the retinal ganglion cells expressing SATB1 in the primate retina, specifically, to ask if cells with homologous morphology to DS cells in mouse express SATB1.
Methods :
Eight retinas from seven male adult marmosets (Callithrix jacchus) and two retinas from two female adult macaques (Macaca fascicularis) were obtained. The retinas were fixed in 4% paraformaldehyde for 1 hour and then incubated with rabbit antibodies against SATB1 and choline acetyl transferase (ChAT). The SATB1-positive ganglion cell nuclei were targeted for intracellular injection with the lipophilic dye DiI. Ganglion cells were classified according to dendritic field size, stratification and branch density.
Results :
In marmoset retina, ~17% of the total ganglion cell population was positive for SATB1. A total of 80 ganglion cells were injected in the marmoset (2 mm to 11 mm eccentricity). The dendritic field diameter of injected cells ranged from 110 to 475 µm and thus they can be collectively classified as wide-field ganglion cells. At least six types of ganglion cell were identified based on their morphology and dendritic field size. In marmoset, SATB1 positive cells included narrow (ON and OFF) and broad thorny cells (33/80; 41%), recursive mono- and bistratified cells (putative DS cells, 13/80; 16%) as well as tufted cells (11/80; 14%). Some of the recursive cells co-stratified with the outer but not the inner ChAT band. In macaque, 19 cells were injected (5 mm to 13 mm eccentricity). Most cells were bistratified (9/19; 47%) but we also found thorny (4/19; 21%) and single examples of recursive and sparse ganglion cells.
Conclusions :
The transcription factor SATB1 is expressed by multiple types of ganglion cells in both macaque and marmoset retina. SATB1 may be used to tease out and characterize thorny and recursive cells (a candidate for DS ganglion cells) in marmoset retina and it may be used to characterize bistratified cells in macaque retina.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.