CHAPTER XIX 



Appearance of Fungi on 

 Direct Examination 



THE various Hyphomycetes which cause infections may be seen in the 

 skin or its appendages either in the filamentous or in the spore stage. 

 In the earliest phase of the infection the filamentous form is noted exclu- 

 sively. Later, spores are observed, and in older infections they predominate. 

 We have thought it best to describe the findings in the sections on the 

 various tissues. 



1. HAIR 



Filaments are rarely noted except in hairs infected with A. schoenleini. 

 Spores vary in size, being largest in the endothrix Trichophyta (T. vio- 

 laceum, T. crateriforme, T. sulfureum). The hair shaft may be noticeably 

 invaded when infection is due to these micro-organisms and less so when 

 it is due to one of the Microspora (such as M. lanosum or M. audouini). 

 With the last-mentioned fungi, the spores are present in the sheath of 

 Henle, externally to the hair shaft. The position of the spores (whether 

 they are external to or are invading the shaft) may sometimes be deter- 

 mined in a freshly made specimen, before the hair becomes too flattened, 

 by moving the objective up and down. 



The appearance of infected hair may be noted in the accompanying 

 illustrations. The predominant infections in hairs are caused by several 

 Microspora. With these, small round spores in mosaic form are seen on 

 the shaft of the hair. In the endothrix infections, the spores are usually 

 seen in linear formation, since they are derived from the filamentous stage 

 by segmentation. When the infection is due to A. schoenleini, the amount 

 of material is less than with other infections, and filaments, which may 

 be irregularly segmented, are commonly observed. In addition, air bubbles 

 are often present. Because of this characteristic picture, favus may be 



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