[Investigations on the pathogenesis of changes in somatic growth of Lymnaea stagnalis (Gastropoda: Pulmonata) experimentally infected with parthenites Opisthioglyphe ranae (Digenea: Plagiorchiida). I. Relative weight of accessory sex organs and synthetic activity of neurosecretory cells].

In the paper an attempt to define pathogenesis of changes in somatic growth of juvenile individuals of the popular freshwater snail Lymnaea stagnalis experimentally infected with parthenites of the trematode Opisthioglyphe ranae was undertaken. Significant enlargement of relative wet weight of examined accessory sex organs (albumen gland, oothecal gland, prostate, male copulatory organ) observed in infected snails permits to explain increase of their somatic growth basing on the hypothesis of disturbances in energetistic budget of the host-as a consequence of reduction by the parasite activity of the snail's reproductive system. Pathogenesis of this phenomenon has probably a complicated character, including also effect of parthenites on activity of the neurosecretory cells that control somatic growth in examined species of the snail. An argument for this standpoint is, observed in infected snails, increase of amount of neurosecretory material and RNA in cytoplasm of these cells (the light green cells of cerebral ganglia), as well as amount of the loose fraction of chromatine in their nuclei.