The potentiality of EMMA-4, the analytical electron microscope, in histochemistry: a review

Mercury pigmentation from industrial exposure. An ultrastructural and analytical electron microscopic study

A study has been made of facial pigmentation resulting from industrial inorganic mercury exposure. Electron microscopy has shown electron-dense 400--900 nm aggregates of 12 nm particles in dermal macrophages and free in the dermis. Use of the analytical electron microscope has enabled direct confirmation of the presence of mercury in these aggregates. The unexpected finding of coexistent selenium is discussed.

Localization of sulphated polysaccharides by X-ray microanalysis in Laminaria saccharina

Analysis of thick sections of Laminaria thallus by X-ray electron microscope microanalysis using EMMA 4 shows that sulphated polysaccharide is located in secretory canals, the "middle lamella" of cell walls and on the thallus surface. Sulphation occurs in the Golgi bodies of specialised secretory cells. These results confirm previous reports using histochemical and autoradiographic techniques.

Electron microscopy and electron probe analysis of mitochondrial cation accumulation in smooth muscle

The contractile responses to barium and the ultrastructure and ionic composition of mitochondria were studied in vascular smooth muscle. In normal rabbit portal anterior mesenteric vein (PAMV) and main pulmonary artery (MPA) smooth muscle mitochondria were frequently associated with the surface vesicles. The average distance between the outer mitochondrial and inner surface vesicle membrane was 4-5 nm. Ba contractures of MPA were tonic and of PAMV were phasic. Incubation of MPA and PAMV with Ba resulted in the accumulation of mitochondrial granules, followed in the MPA by massive mitochondrial swelling. Oligomycin and anoxia inhibited the appearance of mitochondrial electron-opaque granules and prevented the Ba-induced mitochondrial swelling in the MPA. Electron probe analysis of mitochondria in PAMV incubated with Ba and containing granules showed characteristic Ba signals over the mitochondria. Electron probe X-ray microanalysis also showed a highly significant (P < 0.001) correlation of P with mitochondrial Ba, in an estimated elemental ratio of approximately 3 Ba/4 P. Mitochondrial granules were still prominent after block staining of the osmium-fixed, Ba-loaded PAMV, but electron probe microanalysis showed no Ba, but only U, emissions. Tissues incubated with strontium had electron-opaque mitochondrial granules and deposits in the sarcoplasmic reticulum. X-ray microanalysis of mitochondria containing granules showed the presence of characteristic Sr and Ca emissions. The presence of Sr was similarly verified in the sarcoplasmic reticulum. These findings indicate the energy dependent uptake of divalent cations, in association with phosphate, by mitochondria in vascular smooth muscle in situ and the possibility that mitochondria may contribute to the regulation of intracellular divalent cation levels in smooth muscle.