STRUCTURAL SPECIALIZATION IN THE FLAGELLUM OF THE SPERMATOZOON OF THE BLOODSUCKING BUG (RHODNIUS-PROLIXUS HEMIPTERA, REDUVIIDAE)

Spermatozoa of the triatomideo Rhodnius prolixus possess an axoneme with a 9 + 9 + 2 microtubule pattern and two mitochondrial derivatives. Bridges occur between axoneme and mitochondrial derivatives. Two paracrystalline structures embedded in amorphous regions were observed in the mitochondrial derivative. The use of the negative staining technique shows a zig-zag profile in the mitochondrial derivatives due to infolding to the cristae, regularly spaced with approximately 50 nm. This spacing is also observed in the distribution of the strands of particles in the mitochondrial membrana as seen in freeze-fracture replicas. In the P-fracture face of the flagellar plasma membrane, a regular array of the intramembranous particles was observed. This array consists of two rows, with 12-15 particles, and occurs in the space between the mitochondrial derivatives. Thus R. prolixus spermatozoon present a membrane domain, localized in the flagellar region, and bridges between mitochondrial membrane derivatives and the plasma membrane are probably attached to the flagellar components. These membrane specializations may be related to the production of co-ordinated flagellar movement, and can contribute significantly to further phylogenetic studies.