Specificity of ovulation hormones of some basommatophoran species studied by means of iso- and heterospecific injections.

Isospecific injections of intercerebral commissure (COM) extracts of L. stagnalis, L. palustris, and L. ovata (Lymnaeidae) and of extracts of COM/mediodorsal bodies complexes (COM/DB) of Bulinus truncatus (Bulinidae) and Biomphalaria glabrata (Planorbidae) induced oviposition in a high percentage of the experimental snails. Positive results of heterospecific injections between the first three species indicated a likely structural similarity of the ovulation hormones within the genus Lymnaea. The hormones of Lymnaea, Bulinus, and Biomphalaria, however, appeared to be different (negative results of heterogeneric injections).