ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Adaptation to light and darkness involves major transformations of the smooth endoplasmic reticulum (SER) in the retinula cells of the crayfish and other invertebrates, the mechanisms of which are unknown. This paper presents measurements of SER stereological parameters at three levels along the main axis of light-adapted and dark-adapted retinula cells of the crayfish. Both the volume density and the surface density of SER in the perinuclear region of dark-adapted cells are more than double the values found in light-adapted cells. This relationship is inverted in the axoplasm above and below the basement membrane, where SER volume and surface in dark-adapted cells are approximately half of the quantities measured in light-adapted cells. Although this proportional correspondence between changes in separate regions of the cells might suggest merely an intracellular shifting of SER membrane, calculation of the approximate absolute amounts of membrane involved makes this possibility very unlikely. It is concluded that the vast increase of SER in the perinuclear region of dark-adapted cells implies a large input of membrane, which is subsequently removed during light-adaptation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00612039
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