Schistosoma mansoni: visualization with fluorescent lectins of secretions and surface carbohydrates of living cercariae.

Attachment of Schistosoma mansoni cercariae was studied during their explorative movements along a glass surface using labeled lectins as markers. Fluorochrome-labeled lectins selectively labeled surface material produced at the cercarial attachment sites and part of the cercarial surface. The deposited secretions reacted with most of the lectins used but differences in the staining intensity were noted. Secreted material was visualized at the attachment sites within a few seconds after cercarial attachment. The deposited material appeared as "footprints" located at a constant distance from each other. The footprints were formed by a regular cercarial "looping" movement along the glass surface and led to a site of massive deposition of secretions partly covering the body.