Third neutrophil type in red seabream Pagrus major infected with Ceratothoa verrucosa : A case report

タイノエに寄生されたマダイの第3の好中球 : 症例報告

Third neutrophil type in red seabream Pagrus major infected with Ceratothoa verrucosa : A case report

Creators Kondo Masakazu

Creators Yasumoto Shinya

We report that the morphology and cytochemistry of neutrophils from a red seabream Pagrus major infected with numerous Ceratothoa verrucosa (Cv). First, the host was artificially infected with two Cv (adults； usual parasitism), however, finally with 34 Cv (26 Cv were located in gill cavity) except for adults (superunusual parasitism). By observation of blood smear from the host, we noticed the appearance of new type of neutrophil ‘third type； neutrophil-3^{rd}’. The neutrophil-3^{rd} had two types of granules. Both granule types had similar morphology but different cytochemical characteristics to those of ordinary chromophobic granules (oβG-1, oβG-2) of neutrophil from the fish without Cv. In present paper, we call the two granule-types of neutrophil-3^{rd} extraordinary chromophobic granules (type 1, eoβG-1^{Cv3rd} ； type 2, eoβG-2^{Cv3rd}). The eoβG-1^{Cv3rd} showed chromophobic, simple morphology (without stratified structure), peroxidase positive and lack of lysozomal enzymes. On the other hand, the eoβG-2^{Cv3rd} was stratified granule with two-layer structure [inner eosinophilic layer (L0) and outer chromophobic layer (L1)]. Lysozomal enzymes (acid phosphatase, β-glucuronidase and esterases) and peroxidase (PO) were localized in L0 and L1, respectively. However, the lysozomal enzymes were limited in the small central area of L0. Therefore, L0 was interpreted as two-layer structure: L0-0 (inner part in L0) and L0-1 (outer part in L0). Spot formation, a curious phenomenon appeared in PO-stained oβG-2 (positive L1 and negative L0), was also observed in eoβG-2^{Cv3rd}. Both types of extraordinary granules showed negative reaction to Sudan black B, oil red O and Sudan III, however, entire L0 of eoβG-2^{Cv3rd} was stained blue with hematoxylin for counter stain in these preparations.

[ISSN]0370-9361