chromatin in tissues of ectodermal and mesodermal
origin (Alday de Graindorge and Flegel, 1999; Lightner,
1996a). They may not be visible when other fixatives are
used. Since Cowdry type A inclusions are rarely seen in
P. monodon, in situ DNA hybridization assays with a
specific IHHNV probe may be necessary to obtain a
definitive diagnosis.