ENDOTHRIX SPECIES OF TRICHOPHYTON 169 



scalp not due to Microsporum being caused by members of this 

 group of molds. They produce persistent infections without much 

 inflammatory reaction. Although most cases occur in younger life, 

 the infection does not, like microsporosis, tend to disappear at pu- 

 berty, but may persist into adult life. Trichophytosis (endothrix) 

 of the scalp is differentiated from microsporosis by the fact that the 

 organism is found almost exclusively within the hair, the spores being 

 arranged in chains. The hairs tend to break off at the skin level 

 rather than a few millimeters above, leaving a smooth bald spot 

 with few hair stumps and little scaling of the skin. In addition the 

 disease almost always involves some part of the smooth skin as well. 

 The disease is sometimes referred to by its French name, peladoide. 



Many endothrix species of Trichophyton have been described, but 

 most of these names apply to minor variants of two or three species. 

 The important species are Trichophyton tonsurans {T. crateriforme), 

 T. Sabouraudi {T. acuminatum), and T. violaceum. 



T. tonsurans produces large irregular bald patches, the hairs break- 

 ing off flush with the skin early after infection. The skin of the 

 scalp in these bald patches may appear quite healthy. Some hair 

 stumps may be present. They are dark in color, thicker than the 

 normal hairs, and pull out with some difficulty. Microscopic exam- 

 ination reveals the chains of spores in the interior of the hair. They 

 are round, oval, or cylindrical in form and are produced by simple 

 fragmentation of the mycelium into its component cells. They are 

 much larger than the spores of Microsporum and have thick walls. 

 In addition to the bald patches of the scalp, ring-shaped lesions fre- 

 quently develop on the face, neck and hands. 



The colonies on Sabouraud's agar are acuminate, i.e., there is a 

 conical peak projecting from the center of the colony. The closely 

 related T. Sabouraudi forms a colony similar in appearance except 

 that there is a central depression. The peripheral portion of the 

 colony is folded into ridges. The colony is creamy white in color, 

 becoming brownish in some strains; the surface is covered with a 

 fine powdery coat of short hyphae and conidia. The conidia are 

 spherical to pear-shaped or clavate in some strains, borne laterally 

 and at the tips of conidiophores or on only slightly differentiated 

 hyphae, Chlamydospores are formed in abundance in the vegetative 

 mycelium. 



T. violaceum is found in northern Africa, southern Europe, Russia, 

 and America. It produces lesions of the scalp of the same general 

 character as the species just described. In the hair the spores are 

 not so regularly in chains, and they are rounded. The colonies are 



