Structure and ultrastructure of spermatozoa of Chrysomya megacephala (Diptera: Calliphoridae).

The spermatozoa of Chrysomya megacephala are similar to those described for other Brachycera. In this species, the spermatozoa are long and thin, measuring about 590microm in length, of which the head region measures approximately 60microm. The head includes a monolayered acrosome with electron-lucid material, and the shape of the nucleus, in cross-sections, varies from circular to oval with completely condensed chromatin. The centriole was observed in the zone of flagellar implantation, below the "peg" region. In the region of overlap, the followings structures are observed: nucleus, centriolar adjunct, mitochondrial derivatives and axoneme. The two mitochondrial derivatives are of different lengths but similar diameter. The axoneme is of a conventional insectan type with a 9+9+2 microtubular arrangement, with accessory tubules flanked by the electron-dense intertubular material. The male internal reproductive tract consists of testis, vas deferens, seminal vesicle, accessory glands and ejaculatory duct.