. Electron microscopy; proceedings of the Stockholm Conference, September, 1956. Electron microscopy. Transformation of Collagen Fibrils into "Elastin" 231 incubated in phosphate buffer (pH ) containing mg elastase for 6 hours at 37 C. ml. of a penicillin and streptomycin mixture was added to each test tube in the above experiments, and this successfully prevented bacterial contamination. CI. histolyticiini collagenase was kindly supplied b\ Dr. J. D. MacLennan; the elastase was prepared by Hall and Gardiner (2). Samples of three of the substrates (aged 2, 9 and 78 years)
. Electron microscopy; proceedings of the Stockholm Conference, September, 1956. Electron microscopy. Transformation of Collagen Fibrils into "Elastin" 231 incubated in phosphate buffer (pH ) containing mg elastase for 6 hours at 37 C. ml. of a penicillin and streptomycin mixture was added to each test tube in the above experiments, and this successfully prevented bacterial contamination. CI. histolyticiini collagenase was kindly supplied b\ Dr. J. D. MacLennan; the elastase was prepared by Hall and Gardiner (2). Samples of three of the substrates (aged 2, 9 and 78 years) were heated in sterile distilled water to 55 C for 1 hour, to 75 C for a further hour, and finally to 100 C for an hour. Prior treatment with either collagenase or alkaline buffer was of course omitted. Samples for electron microscope examination were taken at each stage in the experiments, and ground gentl> in a glass tissue-grinder until the material appeared milky; drop preparations were made which were shad- owed with chromium and examined in a Siemens electron microscope, type UM 60 C. Counts of the different kinds of elastic structures were made by carefully scanning two grids from each sample. The grids contained 16 squares, and each part of each square was examined in sequence. As about 20 fields covered a square, a total of 640 fields was scrutinised from each specimen. The wide spectrum of morphological change pro- duced exhibited marked age-differences. 1. Heat controls. Heat alone on the untreated 2-, 9- and 78-year-old prepared collagen samples simply produced progressive gelatinisation as the temperature increased, which was complete after boiling for one hour. There was no age-difference, no increase in elastic structures and none of the new structures described below. The fully-formed elastin present in the starting material was some- what reduced in quantity, whilst the component elastin filaments became particularly well defined. Fully-formed elastin. This
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