Morphological characteristics of cyclostom neutrophils observed by Artur Pappenheim

Artur Pappenheim reported a poor description of the morphology of blood neutrophils from lamprey (Lampetra planeri； adult and ammocoetes) and hagfish (Myxine glutinosa) in Folia Haematologica (volume 8, 1909). Here, we inferred on the morphological characteristics of cyclostome neutrophils observed by Pappenheim based on his descriptions and our previous reports. He recognized neutrophilic leukocytes (mature neutrophils) in lamprey (adult and ammocoetes) and hagfish, and neutrophilic myelocytes (immature neutrophils) in ammocoetes and hagfish. This means the existence of specific granules and azure granules. However, the specific granules were considered as an inner layer (L0) of the striated granule (NG2), and the azure granules outer (L1) layer of the striated granule (NG2). The specific granules (=L0 of NG2) would probably have been stained with triacid (purple), acid dyes, and May-Grünwald·Giemsa (MGG； purple), but not with methylgreen-pyronine (MP). The azure granules (=L1 of NG1a) would also have stained purple with MGG, but negative with triacid, acidic dyes and MP.