X-ray microanalysis of endocrine, exocrine and intestinal cells and organs in culture: technical and physiological aspects.

In the present study methods for preparation of cultured cells and organ cultures for analytical electron microscopy are investigated. These methods allow qualitative and quantitative analysis of mobile ions in combination with biochemical or morphological studies. Cultured cells can be easily prepared for analytical microscopy and therefore use of in vitro systems for X-ray microanalysis has increased over the last few years. Two major, anhydrous preparation techniques, by which loss or redistribution of ions is minimized, were used: (1) Cells were cryosectioned and analysis carried out on freeze-dried sections obtained from frozen cell monolayers, pelleted cells or organ cultures. (2)Cells cultured on supports compatible with elemental analysis were frozen after removal of experimental media by rinsing, freeze-dried and analyzed. The first technique was applied to the studies of the elemental content of isolated Langerhans islets and thyroid follicles cultured in collagen gel. The second was used in studies of the ionic changes in enterocytes. Data obtained from organotypic cell cultures and cultures of single cells were compared with analytical data obtained from sections of corresponding tissues, where isolation, culturing and steps in processing such as removal of culture or experimental medium were omitted. It was shown that often culture systems fully acceptable to physiologists have an elemental composition different from that of tissue in situ and can not be regarded as fully normal tissue.