Trichinella spiralis: ultrastructure of the body wall of newborn and muscle larvae.

The body wall structure of muscle and newborn larvae of Trichinella spiralis was studied using transmission and scanning electron microscopy. Differences were found in the structure of the cuticle of the two developmental stages. In the case of the cuticle of the muscle larvae only transverse striae were present whereas the newborn larvae cuticle showed both transverse and longitudinal striations. In the two parasite stages the outer surface of the cuticle appears as a three-layered structure. The hypodermis presents well defined cellular components similar in fine structure in both stages. The plasma membrane of the hypodermal cells in the muscle larvae shows abundant short finger-like projections, that are not present in newborn larvae.