Ultrastructure of the head of ctenomys maulinus spermatozoon with special reference to the nucleus

Feito, R.; Barros, C.

doi:10.1002/mrd.1120050311

Cited by 9 publications

(6 citation statements)

References 7 publications

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“…(Plate Ib). As previously described for other species (Feito & Gallardo, 1976, sperm heads were paddle-like, with a nuclear caudal extension originating at the base of the head at the opposite side of the insertion of the flagellum. Little variation was also found within this group with respect to the general morphological pattern and linear dimensions of spermatozoa ( Table I).…”

Section: Resultsmentioning

confidence: 59%

“…In a progress report , a preliminary survey of the sperm morphology of several species of Ctenomys showed that the genus could be divided into two groups of species bearing symmetrical or asymmetrical sperm cells according to the absence or presence of the nuclear caudal extension. As originally pointed out by Feito & Gallardo (1976), the study of additional species of Ctenomys and other Octodontidae would help to understand the morphofunctional and evolutionary meaning of this structure. We report here new information on the morphometrics of sperm cells in species of the genus Ctenomys distributed in Argentina and Paraguay, with the description of a new morphological type.…”

Section: Introductionmentioning

confidence: 99%

“…maulinus from Chile an asymmetrical sperm type with paddle-like heads and a 'postacrosomic process' which originates at the base of the head and runs parallel to the flagellum. Ultrastructural studies on this peculiar sperm cell, unknown for other mammalian species, showed that this process represented a morphological alteration of the nuclear region and was, therefore, appropriately renamed 'nuclear caudal extension' (Feito & Barros, 1982).…”

Section: Introductionmentioning

confidence: 99%

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On the morphology of spermatozoa of tuco‐tucos, Ctenomys (Rodentia: Ctenomyidae): New data and its implications for the evolution of the genus

1988

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Sperm morphology was studied in 10 species of the caviomorph rodent Ctenomys. Ctenomys argentinus, C. conoueri, C. dorbigny and C.perrensis had symmetric spermatozoa with paddle‐like heads. Ctenomys australis, C. mendocinus, C. porteousi, C. rionegrensis and Ctenomys sp., on the other hand, had spermatozoa with paddle‐like heads but with the tail inserted at one side of the central axis and a nuclear caudal extension originating from the base of the head at the opposite side of the insertion of the tail and running parallel to the flagellum; these spermatozoa are referred to as simple‐asymmetric. In C. yolandae, a complex‐asymmetric morphological type not previously described for the genus was found. This type is characterized by the presence of two nuclear caudal extensions. Symmetric spermatozoa (total length = 52 pm) were shorter than asymmetric (both simple and complex) ones (total length = 87 pm). In spite of these differences, the relative size of heads, midpieces and tails were maintained in the three groups, representing 12%, I I YO and 88% of the average total length, respectively. Within each group of species bearing the same sperm type, a low interspecific variability both in morphological patterns and dimensions of sperm cells was observed. This low interspecific variability associated with the north to south geographical distribution of species having, respectively, symmetric and asymmetric spermatozoa, suggests that these characters appeared at an early stage in evolution of the group, and probably played an important role in the first steps of speciation by promoting reproductive isolation.

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Section: Resultsmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the morphology of spermatozoa of tuco‐tucos, Ctenomys (Rodentia: Ctenomyidae): New data and its implications for the evolution of the genus

1988

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“…The species examined by Sage et al (1986) and by this study barely overlap, so little can be concluded about this discrepancy. (2) Similarly, species with asymmetric sperm (Feito and Barros, 1982) do not form a monophyletic group in our most parsimonious trees, that rather place them in two groups (haigi ϩ sociabilis separate from mendocinus), but this separation is weakly supported. Additional species with asymmetric sperm must be considered to address this issue.…”

Section: Figmentioning

confidence: 86%

The Molecular Phylogenetics of Tuco-Tucos (genusCtenomys,Rodentia: Octodontidae) Suggests an Early Burst of Speciation

Lessa

Cook

1998

Molecular Phylogenetics and Evolution

166

115

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“…Gallardo, 1982;Vitullo et al, 1988;Vitullo and Cook, 1991). The asymmetric sperm, first described by Feito and Barros (1982), is characterized by a paddle-like head with a postacrosomic process that originates at the base of the head opposite the insertion of the flagellum (Fig. 5b).…”

Section: Multiple Origins Of the Asymmetric Sperm Morphmentioning

confidence: 99%

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D’Elı́a¹,

Lessa²,

Cook³

1999

Journal of Mammalian Evolution

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The phylogenetic relationships among 23 individuals representing 14 species of underground hystricognath rodents of the genus Ctenomys were studied by analyzing variation of complete cytochrome b gene sequences. Maximum parsimony, neighbor joining, and maximum likelihood analyses were performed, using the octodontine genera Octodon and Tympanoctomys as outgroups. Our analyses support previous studies based on chromosomes and skull morphology that suggested a clade comprised of Argentinean and Uruguayan populations of C. rionegrensis. This clade is closely related to one comprised of C. flamarioni and the C. mendocinus species complex. Our analyses provide evidence that the symmetric sperm morph, which is common to other South American hystricognath rodents, is the plesiomorphic character state in Ctenomys and in Hystricognathi. Our analyses do not support the hypothesis that the sperm morphs define two major lineages of tuco-tuco species, because species with asymmetric sperm are diphyletic on the basis of cytochrome b sequences, and this morphology appears to have evolved twice in Ctenomys.

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Ultrastructure of the head of ctenomys maulinus spermatozoon with special reference to the nucleus

Cited by 9 publications

References 7 publications

On the morphology of spermatozoa of tuco‐tucos, Ctenomys (Rodentia: Ctenomyidae): New data and its implications for the evolution of the genus

On the morphology of spermatozoa of tuco‐tucos, Ctenomys (Rodentia: Ctenomyidae): New data and its implications for the evolution of the genus

The Molecular Phylogenetics of Tuco-Tucos (genusCtenomys,Rodentia: Octodontidae) Suggests an Early Burst of Speciation

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