Spermiogenesis in the spider, Pisaurina Sp.: A fine structure study

A fine structure study of spermatids and spermatozoa of the spider, Pisaurina sp. demonstrates that early spermiogenesis is similar to other flagellate spermatozoa. An acrosome forms from a Golgi‐derived, acrosomal vesicle, a perforatorium indents acromosome and nucleus, a flagellum with a three‐plus‐nine tubule substructure is formed and nuclear chromatin condenses during spermiogenesis. Divergence from typical spermatozoa includes the presence of a three‐tubule substructure of the central flagellar shaft, progressive rounding‐up of late spermatids with concomitant incorporation of previously formed flagellum. This evidence is presented in terms of its possible functional significance in fertilization and gamete fusion in spiders.