September 1981
Volume 21, Issue 3
Articles  |   September 1981
Light cycle--dependent axial variations in frog rod outer segment structure.
Investigative Ophthalmology & Visual Science September 1981, Vol.21, 395-402. doi:
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      M W Kaplan; Light cycle--dependent axial variations in frog rod outer segment structure.. Invest. Ophthalmol. Vis. Sci. 1981;21(3):395-402.

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      © ARVO (1962-2015); The Authors (2016-present)

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Polarized light microscopy reveals that the structural parameters of Rana pipiens rod outer segments (ROS) are not uniform along the cell axis. In addition to a pronounced birefringence (delta n) gradient found in the basal half of most ROS, periodic delta n bands are seen in approximately 10% of intact ROS isolated by agitating retinas in frog Ringer's solution. These small delta n differences appear as very faint light and dark striations that have a period and width that depends on the duration of light and dark exposure. In ROS from frogs kept on a 14 hr light/10 hr dark cycle at 20 degrees to 22.5 degrees C, the band period for a light-dark band pair is 1.0 to 1.6 micron. Portions of ROS produced during total darkness or constant light are free of distinct periodic bands. Quantitative delta n measurements show that the ROS sections generated in the dark have a relatively higher delta n than those produced in light. Band contrast is irreversibly enhanced when ROS are treated with the calcium ionophore A23187 in the presence of calcium-free saline solution. These results indicate that the synthesis of some calcium-sensitive ROS component is different when the frog is in the dark than when exposed to light.


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