SCHISTOSOMA TURKESTANICA SKRJABIN, 1913: TOPOGRAPHY OF CERCARIAE EMISSION FROM A SPONTANEOUSLY INVADED OBLIGATE INTERMEDIATE HOST LYMNAEA AURICULARIA L., 1758

Abstract

The algorithm of ethology of cercariae (=furcocercariae) of the trematode Schistosoma turkestanica Skrjabin, 1913, when implementing the scenario of the emission process from the naturally invaded mollusk Lymnaea auricularia L., 1758, is constant and consists of two periods. In the first, preliminary, larvae migrate into the subepithelial tissue of the mollusk. In the second, final, consisting of two phases, furcocercariae pierce the epithelial tissue "from the inside out" and go out into the external environment. Initiation by cercariae of the process of exit from the body of the mollusk Lymnaea auricularia L., 1758, excludes the possibility of suspension or reverse development of the sequence of events. Anatomical and topographic areas of the body of the obligate intermediate host Lymnaea auricularia L., 1758, are not limiting factors for the realization of the final phases of the emission process of the cercariae of the trematode Schistosoma turkestanica Skrjabin, 1913. The resulting vector of interstitial migration of cercariae, stochastically oriented in the direction of the shell mouth of the mollusk Lymnaea auricularia L., 1758, brings the larva into the subepithelial tissue in any topographic area of the body of the intermediate host, where the integumentary epithelium borders with the external environment. To denote the anatomical topography of the apical part of the body of the cercarium trematode Schistosoma turkestanica Skrjabin, 1913, we propose to use the term "apical talus organ". The process of emission of cercariae of the trematode Schistosoma turkestanica Skrjabin, 1913, from the body of the mollusk Lymnaea auricularia L., 1758, is invasive for the latter.