366 MEDICAL MYCOLOGY 



the shaft is invaded by staphylococci. Deeper doAvn, the root is surrounded 

 by an inflammatory exudate and atrophies, the epidermis is thin and atrophied, 

 and the corium consists of a dense white fibrous tissue, causing the glazed, 

 scarred appearance of the skin of a bald head. The site of the follicle is oc- 

 cupied by a thin fibrous scar that has destroyed the hair root, leaving perma- 

 nent baldness. 



The sebaceous glands not connected with hair follicles are larger and more 

 racemose. As Malassezia ovalis invades the mouth of the gland, it causes the 

 cells of the mouth to disintegrate more rapidly than usual, because at this site 

 there is very little normal transformation of homy cells to sebaceous material. 

 The cells destroyed by the fungus are more resistant and block the mouth of 

 the gland by a fatty plug; the external part is impregnated with dirt and 

 forms the blackhead, filling the enlarged mouth of the sebaceous gland. The 

 flow of sebum is blocked and collects behind the plug, distending the gland 

 (comedo). This sebaceous plug, which on expression comes out as a little 

 coiled "worm," has been called by Sabouraud the seborrheic cocoon. These 

 plugs are completely soluble in ether. Often these plugs are filled with a fine 

 felted mass of the acne bacillus, which has nothing to do with the disease but 

 finds suitable conditions (fat and anaerobiosis) for growth as a secondary 

 invader. 



As a complication, the comedones may be infected by Staphylococcus 

 alhus or ;8'. aureus, producing the acne pustules. In some individuals, part of 

 the pustules become cicatrized superficially and give rise to keloid scars; in 

 others, the cicatrization is deeper. The gland may become atrophic and its wall 

 reduced to a single row of cells as a result of the excessive sebum fonnation. 

 The inflammation may spread from the gland into the corium, usually without 

 suppuration, giving rise to induration of the corium. The melanoblasts are 

 irritated so that they secrete more pigment, producing a darkening of the 

 skin (chloasma). 



In the scales of relatively quiescent stages, the fungus cells are large, 

 spherical, 8-12/a in diameter, showing occasionally smaller cells and some bud- 

 ding. In the active stage, the fungus cells are smaller, budding forms are 

 numerous, 2-3/x in diameter in the resting stage. The cell and its adherent bud 

 gave the picture described by Unna as his flask bacillus. When the cells are 

 resting, they give the picture described by Sabouraud as morococcus. In the 

 dandruff, some irregular hyphae are seen, 2-3/x in diameter and 15-20/1, long; 

 often slightly bent. As staphylococci in a given field increase, the number of 

 Malassezia cells decrease. 



Attempts to cultivate Malassezia on the usual laboratory media have been 

 unsuccessful. Panja obtained his first successful cultures on Petroff's glycerol 

 medium, an Q^g medium colored with 0.0004/^. gentian violet, to inhibit the 

 staphylococci. The scales should be washed in sterile normal saline to free them 

 from as many extraneous foreign organisms as possible. The washed scales 

 are placed on the upper part of Petroff's medium where the slope has dried 



