Comparative studies of Alaria and Diplostomum metacercariae using SEM

Abstract

Two species of metacercariae belonging to the genera Alaria and Diplostomum were obtained from lizards in Mexico and fish in Peru. Alaria was found in the lungs of Scleroporus grammicus (Mesquito lizard) and Diplostomum was in the intestines of Orestias agasii (Carachi). To study the taxonomy and morphology of these two parasites, their integuments were compared using SEM.The parasites were fixed in 10% formalin, transferred into 2.5% glutaraldehyde and kept in 70% ethanol to be sent to Brigham Young University. Specimens were dehydrated to 100% ETOH and critical point dried. Samples were mounted on stubs using double-stick tape and were coated with approximately 30 nm of gold. The two species were compared using SEM.The integuments of the two species of metacercariae exhibited major differences. In order to achieve maximum absorption, modification of the surface area of primitive parasites is more extensive than in subsequent species. Alaria was uniformly covered with microvilli - characteristic seen in many of the trematodes ‐ ‐ including its anterior sucker region (Fig. 1, 3).