An analysis of the histochemical procedure for sodium ion detection

In vitro differentiation of the human osteosarcoma cell lines, HOS and KHOS

The osteogenic potential of the two human osteosarcoma cell lines HOS and KHOS; a cell line produced by the transformation of the HOS cells by the Kirsten murine sarcoma virus, was studied in vitro. HOS cells cultured more than 2 weeks formed nodules composed of two morphologically distinct layers, an epithelial-like surface cell layer and a collagen-rich inner cell layer. Alkaline phosphatase (ALPase) activity occurred in the plasma membrane of the surface cell layer, and calcified substances developing along collagen fibers were detected in the collagen-rich inner cell layer. The calcified substances were further examined by analytical electron microscopy and were shown to be hydroxyapatite crystals. In contrast, there was neither ALPase nor the deposition of a calcified substance in the KHOS cells.

Elemental composition of pyroantimonate precipitates analysed by electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS) in vitellogenic ovarian follicles of Drosophila

Ca2+ was precipitated with potassium antimonate in vitellogenic follicles of the fruit fly Drosophila melanogaster and the distribution of the precipitates formed was studied by electron microscopy. The microvilli of the oolemma in mid- and late vitellogenic follicles were lined with precipitates. The chemical composition of the precipitates was analysed by electron spectroscopic imaging (ESI). The images produced by inelastically scattered electrons at specific ionization edges were compared, and the non-specific background signals were subtracted by an image processing system. The presence of Ca2+, antimony and oxygen in the precipitates formed could be demonstrated. The elemental composition of the precipitates and of yolk spheres was also analysed by electron energy-loss spectroscopy (EELS). With respect to the precipitates, signals at the calcium L2,3-edge, the oxygen K-edge and the antimony M4,5-edge were recorded without deconvolution and background subtraction. The yolk spheres, which were free of precipitates, gave the characteristic signal of the nitrogen K-edge. The applied techniques combine good ultrastructural resolution with the possibility of analysing the elemental composition of histochemical reaction products and cellular structures.

Evaluation of the pyroantimonate method for detecting intracellular calcium localization in smooth muscle fibers by the X-ray microanalysis of cryosections

The validity of the pyroantimonate method, which has been used for detecting intracellular Ca localization and translocation in smooth muscles, was examined by making cryosections of the relaxed anterior byssal retractor muscle (ABRM) of Mytilus edulis at various stages of procedures for preparing ordinary Epon-embedded sections and determining the elemental concentration ratios of the pyroantimonate precipitate, localized along the inner surface of the plasma membrane, with an energy dispersive X-ray microanalyzer. The concentration of Ca (relative to that of Sb) in the precipitate stayed constant after the procedures of fixation, dehydration and Epon-embedding, while the concentrations of K, Mg, Na and Os showed their respective characteristic changes after the above procedures, being lower than that of Ca in the Epon-embedded sections. The presence of Ca in the precipitate was also demonstrated with an electron energy-loss spectrometer. The localization of Ca underneath the plasma membrane was also observed in the cryosections of the ABRM fibers prepared after mild fixation with acrolein vapor without using pyroantimonate. These results indicate that the pyroantimonate precipitate serves as a valid measure of intracellular Ca localization.

Localization of calcium in fibrocytes associated with the "substantia amorpha" in the skin of toad, Bufo bufo (L.) (Amphibia, Anura)

Using the potassium pyroantimonate-technique in the fibrocytes associated with the calcium-containing granules of the substantia amorpha within the dermis of Bufo bufo numerous electron-dense deposits have been observed. Reaction product lies in the mitochondria, at the plasma membranes and in various vesicular structures. X-ray microanalysis confirmed that pyroantimonate was predominantly associated with calcium. It is suggested that certain organelles of the fibrocytes are capable of sequestering calcium ions and that the fibrocytes are involved in the Ca-metabolism of the substantia amorpha.

Subcellular distribution of ionic components in gastric mucosa of the guinea pig

The topographical distribution of cations, anions and polyanions in the guinea-pig stomach has been studied by ultrastructural cytochemical methods. After fixation with the pyroantimonate-osmium tetroxide solution, variable-sized precipitates were localized in the basolateral extracellular space bordering parietal cells or chief cells but not in that bordering mucus-secreting cells. The basal lamina of all gastric cells disclosed a continuous layer of heavy antimonate deposits. Parietal cells disclosed uniformly fine deposits also on the apical plasmalemma both at the main lumen and in the intracellular canaliculi, and revealed, as well, coarse precipitates in the mitochondria. Fixation with a silver acetate-osmium tetroxide solution yielded nitric acid-resistant, silver deposits confined to the luminal surface of the apical plasmalemma in the main lumen and intracellular canaliculi, the lateral intercellular space, the outer surface of the basal plasmalemma and the basal lamina of the parietal cell. Staining with dialyzed iron demonstrated a glycocalyx rich in acid mucosubstance on the basolateral plasmalemma but not on the apical plasmalemma of parietal cells. In contrast, acid glycoconjugate was visualized on the apical plasmalemma of isthmus cells, mucous neck cells and the transitional cell between isthmus and mucous neck cells but little or no acidic glycoconjugate was demonstrated on the basolateral plasmalemma of these cells. The entire plasmalemma of gastroendocrine cells, unlike other epithelial cells, stained uniformly for acidic glycoconjugate. The dialyzed iron and high iron diamine methods stained the outer compartment of mitochondria in parietal cells intensely and that in other gastric cells lightly. These reagents stained the basal lamina of all gastric cells as did ruthenium red. The several characteristic cytochemical properties of parietal cells presumably relate to the unique secretory activity of these cells and are consistent with the view of the intracellular canaliculi of the parietal cell as the main route for hydrogen and chloride in secretion.

Sodium and calcium localization in cells and tissues by precipitation with antimonate: a quantitative study

Komnick's antimonate technique, which was devised to localize Na+ in cells and tissues, was studied quantitatively. Some modifications, as well as its application to Ca2+ localization, were also investigated. We combined measurements of Na+ and Ca2+ retention in plant roots during the various procedures, electron microscopy, autoradiography, and semiquantitative X-ray microanalysis. We were able to show that (at least in barley roots) antimonate does not precipitate at all with Na+, irrespective of the Na+ content of the tissue or the method of antimonate application. (Even during precipitative freeze dissolution or after freeze drying, no Na+ is precipitated.) By means of Komnick's antimonate technique Ca2+ is trapped within the tissue, but only after serious dislocation. Perspectives for reliable localization of diffusible ions in cells and tissues, by precipitation simultaneously with conventional fixations, are bad.

Ultrastructural localization of calcium around the membrane of the surface connected system in the human platelet

The localization of calcium in the membrane system of human platelets was determined by ultrahistochemical methods equipped with an electron probe x-ray microanalyzer. After potassium oxalate-glutaraldehyde treatment large amounts of electron opaque precipitates were observed around the membrane of the surface connected system. Electron probe x-ray microanalysis clearly defined that the precipitates were composed of calcium oxalate. The localization of calcium on the membrane of the surface connected system was also confirmed even after treatment of the platelets with potassium antimonate-OsO4. These results support a model which depicts the surface connected membrane system taking part in the store and the transport of calcium.

Nonuniform distribution of sodium in the rat hepatocyte

The volume of the nucleus, endoplasmic reticulum (including Golgi complex), mitochondria, and cytoplasmic ground substance was measured in rat hepatocytes by stereological methods. The Na content was also measured by flame photometry. Variations in Na content correlated significantly with variations in volume of nucleus and endoplasmic reticulum. From the correlation parameters, Na concentrations were estimated as follows: nucleus, 108 mM; endoplasmic reticulum (ER) (including Golgie complex) 27 mM; cytoplasm (including and remaining organelles) 16 mM.

Parathyroid morphology in gerbils after thyroidectomy and calcium administration

Morphological studies of the parathyroid glands from adult Mongolian gerbils in which hypercalcaemia had been induced by thyroidectomy and calcium injections for 2-19 days were carried out. The potassium pyro-antimonate technique and subsequent X-ray analysis of the precipitates were used for ultrastructural localization of cations. Ultrastructurally, most (suppressed) chief cells exhibited a dense cytoplasm, medium-sized or large mitochondria, glycogen particles, inconspicuous endoplasmic reticulum and Golgi complex, calcium-containing precipitates mainly in mitochondria and nuclei, and sometimes also lysosomal bodies and accumulations of secretory granules which occasionally seemed to be discharged into cytoplasmic vacuoles. A few parenchymal cells showed a low cytoplasmic density, few organelles, and structurally altered mitochondria, occasionally with associated smooth-surfaced vacuoles. These cells possessed calcium-containing precipitates in mitochondria, smooth-surfaced vacuoles, and also diffusely in the cytosol. It is concluded, that, in the main part of the parenchymal cells, the hypercalcaemia had resulted in a suppression primarily of the synthetic and later also of the secretory activity, and that the calcium-containing precipitation is different in the chief cell variants.

Electron microscopic localization of calcium in vascular smooth muscle

Potassium pyroantimonate has been employed in this study to localize calcium in the vascular smooth muscle of the thoracic aorta of the rabbit. The pyroantimonate ion precipitates sodium, magnesium and calcium. Incubation of theisolated thoracic aorta in a high potassium bathing medium which does not contain sodium, magnesium or calcium depletes the tissue of sodium. Addition of 10.8 mM CaC12 to the incubation medium results in well-localized depositions of reaction product, presumably that of calcium pyroantimonate, in mitochondria, sarcoplasmic reticulum, and at the plasma membrane. Some or all of these organelles may, therefore, play a vital role in the contraction-relaxation cycle of vascular smooth muscle.

Inorganic cations in rat kidney. Localization with potassium pyroantimonate--perfusion fixation

For localization of pyroantimonate-precipitable cations, rat kidney was fixed by perfusion with a saturated aqueous solution of potassium pyroantimonate (pH about 9.2, without addition of any conventional fixative). A remarkably good preservation of the tissue and cell morphology was obtained as well as a consistent and reproducible localization of the insoluble antimonate salts of magnesium, calcium, and sodium. All proximal and distal tubules and glomeruli were delimited by massive electron-opaque precipitates localized in the basement membrane and, to a lesser extent, in adjacent connective tissue. In the intraglomerular capillaries the antimonate precipitate was encountered in the basement membranes and also between the foot processes. In addition to a more or less uniform distribution in the cytoplasm and between the microvilli of the brush border, antimonate precipitates were found in all cell nuclei, mainly between the masses of condensed chromatin. The mitochondria usually contained a few large antimonate deposits which probably correspond to the so-called "dense granules" observed after conventional fixations.