The enzyme cytochemistry and composition of elasmobranch granulocytes

Abstract

Peroxidase, alkaline phosphatase, acid phosphatase, β‐glucuronidase, α‐naphthyl acetate esterase (ANAE), α‐naphthyl butyrate esterase, naphthol AS‐D chloroacetate esterase, acetyl‐L‐tyrosine‐α‐naphthyl esterase (ATNE), tosyl‐L‐lysine‐α‐naphthyl esterase (TLNE) and periodic acid‐Schiff (PAS) were studied in 17 species of elasmobranchs in which granulocytes had previously been identified at the ultrastructural level.Eosinophils, eosinophilic and neutrophilic granulocytes contained variable acid phosphatase, esterases and PAS, but they were strongest in neutrophilic granulocytes; particularly ANAE. Esterases were released into surrounding plasma and therefore probably function as ectoenzymes. In eosinophils and some neutrophilic granulocytes there were indications of weak peroxidase, but this could not be conclusively demonstrated. Alkaline phosphatase was diffuse between granules in some eosinophils of Pavoraja, and (β‐glucuronidase was diffuse in neutrophilic granulocytes of Etmopterus baxteri, otherwise granulocytes lacked these enzymes. Neutrophilic granulocytes stained moderately to strongly for ATNE and weakly and inconsistently for TLNE in Squalus acanthias and Dalatias licha. with a similar reaction in granular lymphocytoid and thrombocytoid cells of Galeorhinus ausiralis and Raja nasuta. The enzyme composition of these granulocytes is discussed.