Spermiogenesis and spermatozoan ultrastructure inPolymorphus minutus(Acanthocephala)

Abstract

The spermiogenesis and spermatozoan morphology of the palaeacanthocephalan, P. minutus were studied by a variety of electron microscopical methods.Spermiogenesis occurs in syncytial clusters of spermatids exhibiting synchronous development. The outstanding events of the spermiogenic process are an enormous elongation of the spermatid nucleus and the eventual breakdown of the spermatid nuclear envelope.The mature spermatozoon is a filiform cell about 60 μm long and motile by propagated undulations. It consists of two parallel elongate components, the single flagellum and the spermatozoan body. The former has a 9 + 2 tubule organization and the latter contains glycogen granules and membrane-bound dense inclusions as well as a region of condensed chromatin of nuclear origin. No mitochondria appear to be present.In the University of Cambridge I should like to thank Professor H. Goodwin for the provision of electron microscope facilities and Mr B. Chapman for teaching me to use them. At King's College, London I am indebted to Professor D. R. Arthur and Professor F. R. Whatley for facilities and Mr H. Edge for excellent technical assistance. The work reported in this paper was initiated during the tenure of an S.R.C. Research Studentship and completed whilst in receipt of a Research Fellowship from the Nuffield Foundation.