Case 75. Cultured Corynebacterium diphtheriae (Neisser stain)

　 　 　 　
　 Metachromatic granules, stained black-brown, are seen at one end or both ends of the rods. 　
　 　 　 　

　

 　 The pathogenicity of C. diphtheriae is determined by diphtheria toxin production.