Biomedical Engineering Reference
In-Depth Information
Materials and Methods
Retinal Preparation
This study utilized retinal tissue from 17 adult rats, 4 guinea pigs, and one
macaque monkey. The average body weight was 284
±
7 g for rats, 386
±
52 g
for guinea pigs, and 4 kg for the macaque monkey.
Rodent eyes were enucleated after decapitation of animals deeply anesthetized
with 10mg/kg Xylazine and 50mg/kg Ketamine HCl. Primate eyes were obtained
from terminally anesthetized macaque monkeys (Macaca radiata) used by other
experimenters. Immediately after enucleation, the anterior portion of the eye and
vitreous were removed in room light and the eye cup placed in bicarbonate-
buffered Ames' solution.
Pieces of retina 1-2mm in diameter (Figure 18.1) were separated from the
retinal pigment epithelium and placed flat on the electrode array, with the
ganglion cell layer facing the array. The tissue was held in place by weighted
nylon netting positioned gently over the array. The preparation was then mounted
on a circuit board attached to an inverted microscope and continuously super-
fused at room temperature with Ames' solution bubbled with 95% oxygen and
5% carbon dioxide. Enucleation, vitrectomy, and dissections were performed
in normal laboratory lighting conditions, likely resulting in substantial retinal
photobleaching.
Figure 18.1. A retinal tissue piece on the stimulation/recording setup, photographed
during an experiment. The hexagonal multi-electrode array is visible in the center. The
nylon netting applies gentle pressure on the tissue.
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