X-ray microanalysis of resting and stimulated rat pancreas

The elemental distribution in acinar cells of rat pancreas was investigated by X-ray microanalysis of thin, freeze-dried cryosections. In the resting cell, the highest calcium concentrations were found in the basal part of the cell (including the endoplasmic reticulum) and in the zymogen granules. Mitochondrial calcium concentrations were low. Zymogen granules were rich in sulphur, but low in phosphorus, sodium and potassium. Stimulation of the pancreas by perfusion in vivo with the cholinergic agonist carbachol caused a significant decrease of the calcium concentration in the basal part of the cell and an increase in the calcium concentration in the apical part of the cell. The mitochondrial calcium concentration was not significantly altered. In addition, increased sodium and decreased potassium concentrations, giving rise to a significant increase in Na/K ratio were observed in all cell compartments measured, except in the zymogen granules.

The reserpinized rat in the study of cystic fibrosis: x-ray microanalysis of submandibular gland and pancreas

The chronically reserpinized rat has been suggested as an animal model for cystic fibrosis. X-ray microanalysis of thick and thin cryosections was carried out to assess elemental redistribution in the submandibular glands and the pancreas of reserpinized rats at the cellular and subcellular level. In the submandibular gland of reserpinized rats, calcium and magnesium concentrations were significantly elevated. Mucus globules, secretory granules, and endoplasmic reticulum were the primary sites of the localization of excess calcium and magnesium. A significant potassium loss from the gland had occurred, particularly from the serous cells. Electron microscopy of conventionally prepared tissue showed marked swelling of the endoplasmic reticulum, especially in mucous cells. The elemental changes in the pancreatic acinar cells of reserpinized rats were reminiscent of elemental redistribution connected with cell death: increased levels of sodium, chlorine, and calcium and decreased levels of magnesium and potassium. Ultrastructural changes included swelling of the endoplasmic reticulum and obstruction of the acinar lumen. It is concluded tha elemental redistribution in chronically reserpinized rats presents interesting parallels with cystic fibrosis.

Cryoultramicrotomy as a preparative method for x-ray microanalysis in pathology

The role of ion shifts in cell injury has become one of the most intriguing fields of application of X-ray microanalysis in pathology. In principle, cryo(ultra)-microtomy is the best preparative method for X-ray microanalysis of diffusible substances. In this review, the following points are discussed: the choice of freezing method and coolant, the use of high molecular weight polymer cryoprotectants and their possible physiological effects the choice of the cryosectioning temperature, and techniques for handling and transfer of sections. Experiences with the sectioning of cryoprotected tissue are presented. Finally, other preparative techniques for microanalysis are compared to cryoultramicrotomy.

Immunofluorescence localizations of proteins in semithin 0.2--1 micron frozen sections of the ear. A report of improved techniques including gelatin encapsulation and cryoultramicrotomy

The present work describes a high resolution technique for locating proteins in frozen sections of the inner ear by immunofluorescence. Dissected organs are encapsulated in gelatin, and sections 0.1--1 micron thick are cut at --100 degrees C in a cryoultramicrotome. These are labelled with antibodies against two cytoskeletal proteins, actin and tubulin. Actin, which had previously only been described in the sensory cells, is found in the supporting cells as well. Tubulin is identified in the supporting cells and in outer spiral nerve fibres.