Histopathological response to turpentine in the white shrimp, Penaeus setiferus

Observations are presented on the inflammatory response to a highly irritative substance, turpentine, injected into the abdominal musculature of the white shrimp, Penaeus setiferus. Injections of the irritant were administered with a tuberculin syringe between the fifth and sixth segments. Penaeid shrimp were found to be highly sensitive to turpentine, even when administered in small dosages. When sterile petroleum jelly was mixed with the turpentine to reduce the dispersion rate, the shrimp's "internal defense mechanism" was able to combat effectively the effect of the irritant. Postinjection observations of the tissues at the site of injection, gill, heart, and hepatopancreas were made at 8, 16, 24, 32, 40, 48, 72, 96, 120, 168, and 240 hr, and at 15, 20, 30, 40, 50, 60, and 120 days. The induced cellular inflammatory response consisted of infiltrating hemocytes and fibrocytes resulting in the formation of fibrous capsules, brown melanized nodules, and fibrous scar tissue in all tissues examined. The gills and hepatopancreas showed considerable tissue destruction early, but were eventually cleared of the histopathological effects of the turpentine and later appeared normal. However, extensive tissue destruction was easily distinguishable in the heart and abdominal muscle even at 120 days postinjection.