The sperm tail axoneme studied at high magnification

Abstract

The axoneme of the insect sperm tail is usually described with the 9 + 9 + 2 formula which refers to 9 accessory tubules surrounding the classical 9 + 2 organelle. When studied with traditional methods the 9 + 9 + 2 pattern is seen as a more or less uniform entity. We describe here some techniques, which show that the axoneme actually is far from uniform and has a structure that in most cases is specific for the insect order. These techniques include fixation with a glutaraldehyde-tannic acid mixture and computer-aided image analysis. Several findings are reviewed here, for instance a nonequidistant distribution of the 13 protofilaments in the wall of axonemal A-tubules, the elliptical shape of the A-tubules and of the accessory tubules of the three related insect orders Psocoptera, Anoplura and Mallophaga, and the existence of singlet microtubules with the same characteristics as A-subtubules in insect order Thysanoptera.

The importance of insect sperm: Sperm ultrastructure of Hermetia illucens (black soldier fly)

“…Furthermore, accessory tubules with electron dense intertubular material has been noted, while more detail, such as the number of protofilaments in the accessory tubules could not be determined. Although it seems likely that Hermetia illucens, as most Brachyceran species (Afzelius et al, 1993), may also exhibit 13 protofilaments in the accessory tubules, the exact number of protofilaments must be confirmed. Additionally, the axoneme is accompanied by two mitochondrial derivatives for most of the flagellum.…”

Is there an orientation-dependent excursion of the Müller body in the ”statocystoid" of Loxodes ?

“…Fixation is a prerequisite for ultrastructural investigation and also facilitates light-microscopic observations (Foissner and Rieder 1983). The application of osmium tetroxide is harmful to chemical bonds and structural detail (Afzelius et al 1993). Loxodes is a particularly delicate ciliate because it lacks a mechanically robust pellicula such as Paramecium possesses.…”