PROBLEMS OF A MUSCLE DISEASE 



photomicrography to be developed fully will require revision and re- 

 definition of the nomenclature of classical histology in order to include 

 those structures which are due to selective absorption as well as those 

 which are due to the effect of physical inhomogeneity and contrasting 

 stains. 



Sections of human muscle photographed in ultraviolet light 

 reveal deeply absorbing transverse zones, spaced at regular intervals, 

 separated by alternate zones of low absorption occurring throughout 

 the length of the muscle fibers. The over-all appearance of the photo- 

 micrographs is the familiar one of cross striation which has long been 

 associated with voluntary muscle. Caspersson, using indirect methods, 

 recently concluded that the isotropic, or dark, striae of muscle revealed 

 by polarized light corresponds in position to the strongly absorbing 

 areas seen in ultraviolet light (3). It has been suggested, moreover, 

 that the absorption which is characteristic of these zones is due chiefly 

 to their content of adenylic acid or adenosine triphosphate. A direct 

 comparison of the position of the striae appearing in polarized light 

 with that occupied by striae appearing in ultraviolet light was made 

 recently, in our laboratory, by comparing half of a field of a given 

 muscle section photographed in polarized light with the remaining 

 half photographed in ultraviolet light. When identical magnifications 

 of the images are compared, inspection of the matched photomicro- 

 graphs leaves no doubt that isotropic zones in muscle revealed in 

 photomicrographs in polarized light correspond exactly to the deeply 

 absorbing striae revealed in the ultraviolet. In sections of muscle 

 taken from cases showing early signs of pseudohypertrophic muscular 

 dystrophy, the transverse zones were very faint, and in some areas 

 almost indiscernible, in marked contrast to the broad compound bands 

 observed in transverse sections of normal muscle. In cross sections, 

 areas of absorption which in normal muscle were punctate and equi- 

 distant in character, were revealed as coalescent areas in a state of 

 apparent disorganization. 



That the method of simplified ultraviolet photomicrography 

 possesses marked advantages over the classical methods of histology 

 and pathology, which depend on staining and examination of speci- 

 mens in visible light, has been brought out convincingly in a study of 

 the histopathological changes associated with muscle disease. In 

 this respect muscle tissue has proved to be a happy choice. Because 



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