Note
The ultrastructural features of spermatogenesis were investigated
in the nudibranch mollusc Spurilla neapolitana. Sperm develop in the proximal
half of numerous sac-like acini which are radially arranged within about ten ovotestis
lobes. Accessory cells line the inner wall of the testicular portion of each
acinus and are connected to developing sperm by numerous desmosomes. Stages
of spermatid development have been divided into precup, cup, postcup, and elongate
stages depending on the general shape of the nucleus.