Abstract
Purpose :
Astrocytes and capillaries are the main non-neuronal elements that sustain RGC axonal viability. To characterize the effect of myopia on inner retinal capillaries and co-localized astrocytes, we developed an immunostaining protocol for quantifying cell-density, distribution and morphology of these cells in juvenile marmosets to serve as normative data.
Methods :
Eight retinal whole-mounts from five juvenile marmosets (age 293±90.56 days) were labeled with Isolectin and anti-GFAP to visualize the inner retinal plexus and astrocytes. Using single-photon confocal microscopy, six images were taken per eye at the superficial, intermediate, and deep layers (z-stacks: 640x640 pixels X axis, 10 pixels Y axis). The average number of capillary branch points (CBP), astrocyte bodies (AB) and astrocyte primary processes (APP) in the central and retinal periphery were quantified using Photoshop. The far-temporal retina in two eyes was punctured for retinal quadrant orientation during quantification.
Results :
Capillaries got thinner and branched more towards the periphery (CBP center 154.06±40.18, periphery 279.8±92.0, p=0.97). The average number of AB and APP was lower in the parafoveal retina (AB center 166.88±33.21, periphery 374.73±58.85, p=0.58; APP center, 3.94±0.46, periphery 4.20±0.46, p=0.60). Both younger and older marmosets had similar CBP, AB and APP (p>0.05). Quadrantal analysis showed highest number of CBP to be nasal (131.25±54.8), followed by temporal (115±63.64), superior (111.25±30.05) and inferior (103.75±22.98). The number of AB and APP seemed unaffected by retinal location (average AB 144.38±1.77; average APP 3.79±0.12, p>0.05). Astrocyte morphology appeared more radial in the central retina (75%) and more stellate in the peripheral retina (62%).
Conclusions :
The superficial retinal capillary plexus and co-localized astrocytes can be imaged in juvenile marmosets using Isolectin and anti-GFAP immunostaining. Like other animals, the inner retina of marmosets had greater number of elongated astrocytes with capillaries that branched less in the central retina near the optic nerve head than in the periphery. This pattern did not change with respect to retinal quadrant or age in juvenile marmosets, possibly suggesting astrocyte morphology and numbers remain stable across the periphery during the first year of life in juvenile marmosets.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.