Life Sciences Commons^™

The Physical State Of Potassium In Frog Skeletal Muscle Studied By Ion-Sensitive Microelectrodes And By Electron Microscopy: Interpretation Of Seemingly Incompatible Results, L. Edelmann

Scanning Microscopy

According to the commonly accepted membrane pump theory most of cellular K⁺ ions are freely dissolved in free cellular water; the alternative association-induction hypothesis postulates that the bulk of cellular K⁺ is adsorbed (weakly bound) to cellular proteins which are maintained in a specific labile state in the cytoplasm of a living cell. K⁺ activities measured with ion-sensitive microelectrodes in the cytoplasm of frog skeletal muscle seem to confirm the claim that most of cellular K⁺ ions are free in cellular water. On the other hand, it is evident from electron microscopic ion binding studies that …

Olfactory And Nasal Respiratory Epithelia, And Foliate Taste Buds Visualized With Rapid-Freeze Freeze-Substitution And Lowicryl K11m Embedding. Ultrastructural And Initial Cytochemical Studies., Bert Ph. M. Menco

Scanning Microscopy

Rat olfactory and respiratory epithelia and Rhesus monkey taste buds were studied with rapid-freeze, acetone/0.1% uranyl acetate freeze-substitution and low-temperature Lowicryl K11M embedding, usually in the absence of other chemical fixation and cryoprotection procedures. Ultrastructural features of mucus, cytoplasm, including cytoskeletons, and membranes were better retained than with conventional methods. Some major examples: The mucus of the olfactory epithelium consisted of a single layer; that of the respiratory epithelium had an electron-opaque sol layer surrounding cilia and microvilli below a thin laminated electron-lucent gel layer. Taste-bud pores displayed a foam-like opaque secretory product, resembling the contents of secretory granules within …

X-Ray Microanalysis Of Calcium Containing Organelles In Resin Embedded Tissue, G. Nicaise, I. Gillot, A. K. Julliard, E. Keicher, S. Blaineau, J. Amsellem, J. C. Meyran, M. L. Hernandez-Nicaise, B. Ciapa, C. Gleyzal

Scanning Microscopy

The localization of calcium in cell organelles at the electron microscope level is often achieved through cytochemical techniques, and verified by X-ray microanalysis. Various methods have been used to cytochemically detect calcium or calcium-binding sites : calcium loading, calcium substitution by strontium, barium, or even lead, and calcium precipitation by oxalate, phosphate, fluoride, or pyroantimonate. Their results may have heuristic value, particularly in preliminary studies of poorly known cell types. A complementary and more physiological approach is offered by quantitative measurement of the total calcium content of organelles after cryofixation.

Resin embedding is less demanding than cryomicrotomy and gives better …