タイノエに寄生されたマダイに観察される第2の好中球

Second neutrophil type observed in red seabream Pagrus major with parasitized Ceratothoa verrucosa

Creators Kondo Masakazu

Creators Yasumoto Shinya

Creators Takahashi Yukinori

In previous papers, we reported that the morphology and cytochemistry of neutrophil from red seabream Pagrus major infected with Ceratothoa verrucosa (Cv) were different to that of fish without Cv. Here, we call the neutrophil ‘first type； neutrophil-1^{st}’. By observation of blood smear from 3 fish (3 years old) infected with more than 4 Cv (5,5 or 14 parasites/fish), we noticed the appearance of new type of neutrophil, ‘second type； neutrophil-2^{nd}’. The neutrophil-2^{nd} 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-2^{nd} extraordinary chromophobic granules (type 1, eoβG-1^{Cv2nd}； type 2, eoβG-2^{Cv2nd}). The eoβG-1^{Cv2nd} showed chromophobic, simple morphology (without stratified structure), peroxidase positive and lack of lysozomal enzymes. On the other hand, the eoβG-2^{Cv2nd} was stratified granule with two-layer structure [inner eosinophilic layer (L0) and outer chromophobic layer (L1)]. Lysozomal enzymes (acid phosphatase, β-glucuronidase (β-Glu) and esterases) and peroxidase (PO) were localized in L0 and L1, respectively. The β-Glu was detected in a few L0. Both types of extraordinary granules　showed negative reaction to Sudan black B, oil red O and Sudan III, however, L0 of eoβG-2^{Cv2nd} was stained blue with hematoxylin for counter stain in these preparations. Spot formation, a curious phenomenon appeared in PO-stained oβG-2 (positive L1 and negative L0), was not observed in eoβG-2^{Cv2nd}. The neutrophil-2^{nd} was only granulocyte type in the head kidney, but two types of granulocytes, neutrophil-2^{nd} and large granulocytes, were observed in the spleen of the fish infected with Cv.

[ISSN]0370-9361