Morphological and cytochemical characteristics of neutrophils from larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri

Two types of stratified [two-layer； inner layer (L0) and outer layer (L1)] granules were observed in the neutrophils (neutrophil granule, NG： type 1, NG1a； type 2, NG2) of larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri collected in a tributary of the Koyagawa River in Yamaguchi Prefecture. The NG1a consisted of chromophobic L0 and chromatophilic L1. On the other hand, the NG2 had chromatophilic L0 and chromophobic L1. The L1 of NG1a and L0 of NG2 showed a variety of colors [eosinophilic or basophilic (orthomethylenophilic or metaazurophilic)] depending on the staining conditions. These layers were positive for alkaline phosphatase, α-naphtyl acetate esterase and Sudan black B. Some enzymes, such as acid phosphatase, ꞵ-glucuronidase, and naphthol AS-D chloroacetate esterase were detected in the L0 of NG2. The neutrophils lacked α-naphtyl butyrate esterase and peroxidase.