Blood cellular components in wild caught Muraena helena (Muraenidae)
Wild caught moray eels, Muraena helena L. 1758, were collected in Adriatic Sea near Dubrovnik, Croatia. Blood cells were evaluated by Natt-Hericks and MGG stain. Mean haematocrit was 23.22 ± 3.13. RBC count was 4.007 ± 1.60 x 1011/L. Thrombocytes were present in four forms. Average WBC count was 3.37% of the total cell count. On average lymphocytes accounted for 15.05%, up to maximally 23% of WBC. Monocytes were least present (on average 4.59%). Basophiles or eosinophiles were not found and analogous to the reports in some kin species (Anguilla anguilla) they probably don’t exist in spotted moray at all. Two types of granulocytes both with eccentric, round or bilobed nuclei were the most abundant leukocytes (49.13% and 31.23% of WBC respectively). The prevailing granulocyte was standard neutrophile (heterophile) found in all fish species. Second most abundant granulocyte type had the shape, size and cytoplasmic granules identical to the neutrophile but MGG stain revealed its high cytoplasmic affinity towards basophilic dye. No intermediate phases between two types were found indicating they are diverse cell types. This second granulocyte type may be a distinctive feature of innate immunity of spotted moray.