Osmium tetroxide-zinc iodide reactive sites in the photoreceptor cells

DE IRALDI, AMANDA PELLEGRINO; SUBURO, ANGELA MARIA

VISION RESEARCH

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1971 vol. 11 p. 27 - 31

0042-6989

In a previous study it had been shown that after osmium tetroxide-zinc iodide (ZIO) fixation there are heavy electron dense deposits in the outer segments of rat photoreceptor cells. A positive reaction can also be observed in synaptic vesicles from the photoreceptor cells. Our observations in the retina of the pigeon seem to indicate that the reaction is confined to the rod outer segments, as no electron dense deposits could be observed in the cone outer segments. ZIO reactive synaptic vesicles can also be observed in the photoreceptor nerve endings of the pigeon. To study the light sensitivity of the ZIO reactive material present in the rod outer segment, we fixed the retina of rats subjected to 96 hr of either continuous illumination or darkness. It was observed that the electron dense deposits are more concentrated after continuous illumination. The reactivity of different substances with the ZIO mixture was studiedin vitro. Considerations are made about the possible relationship between ZIO reactive material and the visual pigments