Carboxylic Esterase Activity of Procyotrema marsupiformis Harkema and Miller, 1959 (Diplostomatidae)

The histochemical localization of carboxylic esterase activity was studied for Procyotrema marsupiformis, a parasite of the pancreatic duct of the raccoon. Appropriate substrates and inhibitors were utilized to differentiate simple esterases from cholinesterases. In all tests the pharynx demonstrated the most intense reaction, apparently due to a mixture of nonspecific (simple) esterases and acetylcholinesterase. A strong reaction for acetylcholinesterase activity was obtained in the oral sucker, acetabulum, pseudosuckers and their glandular cells, tegument and subtegumentary cells in the region of the oral sucker, nerve tissue, Laurer's canal, oviduct, descending uterus, crypts of the holdfast, bursa, genital papilla, and excretory pore. Nonspecific esterases were indicated in the subtegumentary cells of the holdfast, the outer tunics of the testes and seminal vesicle, vas deferens, prostatic cells, and within the crypts of the holdfast. Pseudocholinesterase was not demonstrated.