Fluorescence microscopy study on the cytoskeletal displacements during sperm differentiation in the bush-cricket Tylopsis liliifolia (Fabricius) (Orthoptera: Tettigoniidae)

A study by fluorescence microscopy has been carried out on male gametes from testicular follicles, seminal vesicles, spermatophores, and seminal receptacles of the bush cricket Tylopsis liliifolia, focusing the attention on localization and movements of F-actin and atubulin during sperm differentiation, since data in this respect are lacking in the Orthoptera. F-actin and a-tubulin positivity was detected in the testicular follicles, in particular at the bridges connecting spermatids of a same clone and around their nucleus, during the first differentiation stages. During the following differentiation stages in the testes, F-actin was found at one of the spermatid poles and then, during nucleus elongation, at the whole acrosomal region. A peculiar F-actin-positivity was found at the flagellum, more markedly immediately posterior to the nucleus, at the basal body region of the gametes from the testicular follicles and from the other examined districts. Other interesting data from our investigations concerns the a-tubulin displacements during the differentiation stages of the spermatid and a constant absence of atubulin-positivity where the centrioles are located. No positivity was also found for both atubulin and nuclear markers at the anterior region of the gamete, where the acrosomal wings are localized. Our results, compared with what is so far known in literature for the insects, lead us to assert that microfilaments and microtubules undergo gradual displacements, markedly in the testicular follicles, during the morphogenesis of the male gamete of T. liliifolia aimed to its organization and motility and probably also to its interaction with the female gamete.