The action and interaction of calcium and alkali chlorides on eggs of Limnaea stagnalis and their chemical interpretation

SUMMARYI. Changes in the permeability, especially to ions, of the cell membrane during fixation for electron microscopy are likely to have consequences for the ultrastructure of cells to be investigated.2. Ion permeability changes of single egg cells of Limn, aea slag,aalis L. were studied by a microconductometric method.3. To this end a conductometric cell was developed with electrode surfaces of o.14 mm 2 and a cell constant of o.05. Its volume is about 26 times that of an egg cell. Conductivity changes, depending on salt concentration of the medium, were recorded as variations of a iooo cycles/see current through the conductivity cell.4. By means of electrical cytolysis of the egg cell in distilled water its salt content could be determined as to correspond to a solution of about o.o4 M NaC1.5. On fixation with OsO~ the cell membrane becomes completely permeable to ions in a few seconds. On fixation with glutaraldehyde, ions leave tile egg cell only very slowly, as they do in distilled water.6. On the basis of these observations the optimal ionic composition of an OsO~ fixing solution is discussed, taking into account the establishment of a Donnan equilibrium between egg content and fixative medium.

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The action and interaction of calcium and alkali chlorides on eggs of Limnaea stagnalis and their chemical interpretation

Cited by 8 publications

References 3 publications

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Ion permeability of the egg of Limnaea stagnalis L. on fixation for electron microscopy

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