We describe, for the first time, the ultrastructure of the spermatozoa of four species of the genus Tupinambis (Squamata, Teiidae). We identified seven polymorphic characters within this genus: the presence and shape of the perforatorial base plate, the presence of the epinuclear lucent zone, the presence of a unilateral ridge in the acrosome, the presence of a central density within the proximal centriole, the number of mitochondria and dense‐bodies sets, and the shape of mitochondria. We analysed the evolution of the seven polymorphic characters by mapping them onto a current phylogeny of the species of Tupinambis, using the teiids Ameiva ameiva and Cnemidophorus sexlineatus as outgroups. Our results indicate that sperm ultrastucture characters, although of great value for phylogeny at higher taxonomic levels in reptiles and other groups, are poor predictors of phylogeny when considering the species of Tupinambis studied here. We failed to identify evidences that homoplasy in sperm ultrastructure among the species of Tupinambis is due to convergent adaptation, suggesting that the polymorphism may be selectively neutral in this group.

We investigate the evolution of sperm ultrastructure of three species of Boidae (Epicrates cenchria, Boa constrictor amarali, and Corallus hortulanus). Spermatozoa of these species are Wliform consisting of a head region, containing the nucleus and acrosome complex, a midpiece, and a tail region subdivided into principal piece and endpiece. Multilaminar membranes and extracellular microtubules were observed next to the plasma membrane of the spermatozoa. The following diVerences were observed among the species: ridge on acrosome surface in Boa constrictor amarali (absent in Epicrates cenchria and Corallus hortulanus), stopperlike perforatorium base plate in Boa constrictor amarali and Epicrates cenchria (absent in Corallus hortulanus), rounded mitochondria in transverse section in Epicrates cenchria and Corallus hortulanus (irregular in Boa constrictor amarali). We mapped sperm characters onto two phylogenies based on morphological (Kluge in Misc Publ Mus Zool Univ Michigan 178:1-58, 1991) and molecular (Austin in Copeia 2:341-352, 2000) data, using a number of squamate species as outgroups. We identiWed 31 unambiguous character transformations in the morphological phylogeny and 30 in the molecular phylogeny, but only 13 and 12 transformations, respectively, are possible synapomorphies. We identiWed novel sperm synapomorphies, which were common between the morphological and molecular phylogenies: absence of perforatorium base plate and mitochondria arranged as sinuous tubes in oblique section (Serpentes), acrosome vesicle not subdivided and Wbers 3 and 8 at the anteriormost region of principal piece (Boidae), and absence of an electron dense structure inside the proximal centriole (Elapidae + Colubridae). Our results suggest greater agreement between sperm ultrastructure and gross anatomical characters. In addition, we found no tendency for more homoplasies in the sperm head than in the Xagellum, as recorded in previous studies.

The present study was undertaken to elucidate some aspects about the nature of the spermatozoon ultrastructure of Crotallus durissus using cytochemical methods. We also provide for the first time the ultrastructural description of this species spermatozoon. Cytochemical studies of spermatozoa have not been performed so far in the Serpentes, and species spermatozoon may prove helpful to better understand the reproductive biology of this group. Besides the synapomorphies of the Squamata and Serpentes, the C. durissus spermatozoon possess the following: circular acrosome tip; rounded perforatorium tip with a stopper-like basal modification; bilateral stratified laminar structures; central electron-dense structure within the proximal centriole; fibrous sheath extending until the level of the second mitochondrial ring; rounded mitochondria in cross-section, but with variable shape and organization in longitudinal and oblique sections, respectively; linear annulus; developed multilaminar membranes in the nuclear region and the midpiece. The formation of membrane filipin-sterol complexes occur sparsely along the head region, specially around the nucleus; the complexes were also present in the midpiece membrane and scarcely lining the flagellum. The complexes were present in the different layers of the multilaminar membranes. The ethanolphosphotungstic acid (E-PTA) treatment releaved the presence of basic proteins in acrosome vesicle, pericentriolar material, peripheral fibers of the axoneme and fibrous sheath. The tannic acid technique revealed the microtubules of the centrioles and the axoneme; the extracellular tubules encircling the spermatozoa and those spread in the epididymal lumen were also observed. However, the immunocytochemistry assay using antibodies against alphatubulin and beta-tubulin, the primary microtubule monomers, does not support the existence of composition similarity between these tubular structures, since the extracellular tubules were not labeled by the antibodies. The results obtained in this work demonstrate that the utilization of electron microscopic techniques may provide relevant information to the study of ophidian reproductive biology, particularly in analyses concerning spermatozoal ultrastructure.

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Tavares-Bastos, L., Cunha, L.D., Colli, G.R. and Báo, S.N. 2007. Ultrastructure of spermatozoa of scolecophidian snakes (Lepidosauria, Squamata). -Acta Zoologica (Stockholm) 88 : [189][190][191][192][193][194][195][196][197] We provide a detailed description of the sperm ultrastructure of three species of scolecophidian snakes, Leptotyphlops koppesi (Leptotyphlopidae), Typhlops reticulatus (Typhlopidae) and Liotyphlops beui (Anomalepididae), and make comparisons with the spermatozoa of Ramphotyphlops waitii (Typhlopidae) (Harding et al. 1995). All the species studied bear synapomorphies of Squamata and Serpentes. Among scolecophidian snakes, we identified eight polymorphic characters. Previous analyses of molecular and somatic morphological data provide equivocal solutions to the relationships among Anomalepididae, Leptotyphlopidae and Typhlopidae. A close relationship between Anomalepididae and Typhlopidae is corroborated by two characters of sperm ultrastructure, presence of an electron-dense structure inside the proximal centriole and rounded mitochondria in transverse sections of T. reticulatus , Li. beui and R. waitii , whereas the absence of the ridge on the acrosome surface of Le. koppesi and T. reticulatus support a closer relationship between Typhlopidae and Leptotyphlopidae. The differences observed in sperm ultrastructure within Typhlopidae suggest the existence of snake intrafamilial polymorphism. The sperm characters of blindsnakes contain significant phylogenetic information and may provide important data for snake phylogenetic reconstructions.