Ultrastructure of the nebenkern during spermatogenesis in the praying mantid Hierodula membranacea

Spermatogenesis leads to the formation of functional sperm cells. Here we have applied high-pressure freezing in combination with transmission electron microscopy (TEM) to study the ultrastructure of sperm development in subadult males of the praying mantid Hierodula membranacea. We show the ultrastructure of different stages of sperm development in this species. In addition, we have applied serial-section electron tomography of the nebenkern to demonstrate in three dimensions (3D) that this organelle is composed of two interwoven segments that are connected by a zipper-like structure at opposing positions. Our approach will enable further ultrastructural analyses of the nebenkern also in other organisms.