. Electron microscopy; proceedings of the Stockholm Conference, September, 1956 . Fig. 1. Typical example of skin-lype elastin from llic fresh dermis of an intlividiial aged 66 years. This variant forms ')5"„ of nauiral (fully-formed) elastin and contains a fair amount of dense amorphous material (elastomucin). The other variants (filamenting and large networks) have less elastomucin so their component filaments are better visua- lised. Magnification Fig. 2. Typical "moth-eaten" fibre (MEF) from the prepared dermal collagen of a 2-ycar-old child after incubation for 24 h
. Electron microscopy; proceedings of the Stockholm Conference, September, 1956 . Fig. 1. Typical example of skin-lype elastin from llic fresh dermis of an intlividiial aged 66 years. This variant forms ')5"„ of nauiral (fully-formed) elastin and contains a fair amount of dense amorphous material (elastomucin). The other variants (filamenting and large networks) have less elastomucin so their component filaments are better visua- lised. Magnification Fig. 2. Typical "moth-eaten" fibre (MEF) from the prepared dermal collagen of a 2-ycar-old child after incubation for 24 hours at 37 C with collagenase (CI. histolyticiini) in phos- phate bufter pH Note the beaded fibrils and numerous "beads" in the background. Magnification 10,000. Thus the starting material consisted simply of stri- ated collagen showing slight "standard"" collagenase change (7) and the usual ciuantity of fully-formed elastin. These components responded to heat in identical fashion to the heat controls described above. However, samples from the child and young adult substrates gave a very different picture. 85-90 "o of the collagen was digested, and the deposit consisted mainly of typical MEF (fig. 2). Gentle grinding fragmented these thick, dense fibres into portions of different lengths accompanied by a large number of angular, dense bits. These MEF proved relatively heat-resistant, a considerable degree of breakdown occurring only after boiling. In addi- tion many portions of MEF were found to terminate as "elastic networks" (MEFC) and a number of isolated networks (MN) were also seen. MEF conversions (MEFC) (figs. 3 and 4) denote moth-eaten fibres transforming into "elastin net- works", identical with the manufactured networks (MN) described below. In the two child substrates some of the MEF appeared to be transforming into sheet-like elastin in addition to the usual network type and heat markedly increased the numbers
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