Re-examination of spermatogenesis of Multicotyle purvisi (Platyhelminthes, Aspidogastrea).

Examination of spermatogenesis in Multicotyle purvisi revealed that the process follows the classical pattern previously described for many parasitic platyhelminths, especially other Aspidogastrea and Digenea. Free flagella (with an intercentriolar body between the basal bodies and with striated flagellar rootlets) and a median cytoplasmic process grow from a zone of differentiation. The flagella then fuse with the process in a proximo-distal direction and nucleus and mitochondrion grow out into the elongating spermatid. Spermatids are pinched off at the base, and rootlets and intercentriolar body remain behind in the residual cytoplasm. It is suggested that the aberrant processes described in an earlier report constitute a pathological condition or a response to stress. Changes in the intercentriolar body during spermiogenesis are documented and for the first time in a platyhelminth it is demonstrated that rootlets and intercentriolar bodies are discarded and left behind in the residual cytoplasm.