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

Abstract

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.

Quantitative determination of elements by energy dispersive X‐ray microanalysis and atomic absorption spectrometry in egg cells of Lymnaea stagnalis

“…A droplet of the same size, containing 0.2"" glutaraldehyde pH 3-4 was added, sucked back after 15 s and then the specimen was air dried in a few seconds. During the short washing time no loss of ions from the cells occurs (Elbers, 1966). In the dried down egg the four cell regions remain discernible as the cells originally lie in one plane (Fig.…”

The Osmotic Effects of Electron Microscope Fixatives

“…Elbers (1966) that of the tissue, the total osmolarity of the fixative including glutaraldehyde being much higher (Torack, 1965 ;Schultz and Karlsson, 1965) . Thus Schultz and Karlsson found that rat brain perfused with glutaraldehyde gave results similar to those with hypotonic fixatives when the total osmolarity of the fixative was the same as that of cerebrospinal fluid, whereas good results were obtained when the buffer osmolarity was that of the cerebrospinal fluid and the total osmolarity of the fixative including glutaraldehyde much higher .…”

Studies on semipermeability and electrical characteristics in membranes of Chara cells fixed with glutaraldehyde

“…Bone and Denton (1971) reported that semipermeability of the plasma membrane was maintained during glutaraldehyde treatment in the reflecting cells on the scales of sprat. Elbers (1966) reported that glutaraldehyde did not induce an increase in ion leakage during 10-min treatment with 3% glutaraldehyde in eggs of Limnaea stagnalis. The effect on electrical characteristics has been analyzed in cardiac Purkinje fibers.…”