Embryonic development of the degu, Octodon degus

Rojas, Mariana; Montenegro, M. A.; Morales, Bárbara

doi:10.1530/jrf.0.0660031

Cited by 29 publications

(23 citation statements)

References 11 publications

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“…Paternal care and communal breeding characterize the desert-living striped mice Pillay 2003, 2004). In addition, we provide the first ossification-sequence data for the degu, Octodon degus, a small to medium-sized, diurnal, semi-fossorial and herbivorous caviomorph rodent common to the central region of Chile (Mess 2007;Rojas et al 1982). Studies of communal breeding in O. degus have shown that this rodent lives in groups with polygamous social structure (e.g.…”

Section: Introductionmentioning

confidence: 99%

Skeletogenesis and sequence heterochrony in rodent evolution, with particular emphasis on the African striped mouse, Rhabdomys pumilio (Mammalia)

et al. 2010

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Data documenting skeletal development in rodents, the most species-rich 'order' of mammals, are at present restricted to a few model species, a shortcoming that hinders exploration of the morphological and ecological diversification of the group. In this study we provide the most comprehensive sampling of rodent ossification sequences to date, with the aim of exploring whether heterochrony is ubiquitous in rodent evolution at the onset of skeletal formation. The onset of ossification in 17 cranial elements and 24 postcranial elements was examined for eight muroid and caviomorph rodent species. New data are provided for two non-model species. For one of these, the African striped mouse, Rhabdomys pumilio, sampling was extended by studying 53 autopodial elements and examining intraspecific variation. The Parsimov method of studying sequence heterochrony was used to explore the role that changes in developmental timing play in early skeletal formation. Few heterochronies were found to diagnose the muroid and caviomorph clades, suggesting conserved patterning in skeletal development. Mechanisms leading to the generation of the wide range of morphological diversity encapsulated within Rodentia may be restricted to later periods in development than those studied in this work. Documentation of skeletogenesis in Rhabdomys indicates that intraspecifc variation in ossification sequence pattern is present, though not extensive. Our study suggests that sequence heterochrony is neither pivotal nor prevalent during early skeletal formation in rodents.

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Section: Introductionmentioning

confidence: 99%

Skeletogenesis and sequence heterochrony in rodent evolution, with particular emphasis on the African striped mouse, Rhabdomys pumilio (Mammalia)

et al. 2010

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“…Octodon degus were maintained in the laboratory at 20-22°C under natural light and with free access to food and water. Foetuses were obtained according to the previously described method (Rojas et al 1982), as follows: females presenting a perforated vaginal membrane were joined with selected males; the initial day of pregnancy (day 0) was determined by the presence of spermatozoa in vaginal smears which were taken daily. Females were isolated and embryos obtained by laparatomy.…”

Section: Methodsmentioning

confidence: 99%

“…Octodontidae; Suborder Caviomorpha; Order Rodentia) has a longer period of gestation (range 87-93 days, see Weir 1974) than that of other rodents, and this permits an accurate study of the different phases of development. The embryonal development of this species has been analysed recently (Rojas et al 1982), and in 41-day post-coitum embryos a testis could be recognized.…”

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confidence: 99%

Foetal meiosis in the testis of the rodent Octodon degus

1984

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Different stages of meiotic prophase have been studied in foetal testes of the rodent, Octodon degus, using the light and electron microscope. Special attention was focused on the ultrastructural morphology of these meiotic cells in comparison to pre-spermatogonia of foetal testes and meiotic spermatocytes of the adult male testis. Meiosis occurs in only a few cells located among fibroblasts of the tunica albuginea or in the region of the gonadal blastema. The foetal meiotic process resembles adult meiosis in its ultrastructural characteristics; typical pachytene synaptonemal complexes and leptotene or diplotene axial elements appear associated to the chromatin. This process occurs at the same foetal age that meiosis commences in the ovary, thus reinforcing the idea that both meiosis-inducing and meiosis-preventing substances are secreted in both sexes. The intra-or extracordonal localization of the germ cells would be an important factor in determining the cells' response to these substances.

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“…2011a). After a gestation period of 87 ± 3 days (Rojas, Montenegro & Morales ), females give birth to an average of 6 ± 1 precocial offspring (14 g, Long & Ebensperger ). The lactation period is relatively short, lasting ~30 days.…”

Section: Introductionmentioning

confidence: 99%

“…Sexual maturity occurs~6 months after birth (Mahoney et al 2011), with the primary mating season taking place during the late, austral fall (June) . After a gestation period of 87 AE 3 days (Rojas, Montenegro & Morales 1982), females give birth to an average of 6 AE 1 precocial offspring (14 g, Long & Ebensperger 2010). The lactation period is relatively short, lasting~30 days.…”

Section: Introductionmentioning

confidence: 99%

Masculinized females produce heavier offspring in a group living rodent

Correa

León

Ramírez‐Estrada

et al. 2016

Journal of Animal Ecology

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Alternative morphotypes have been reported less frequently in females than in males. An exception to this rule is the gradient of phenotypical masculinization reported in some female mammals, in which feminized and masculinized females represent two opposite ends along this gradient. These phenotypical differences originate during prenatal development as the consequence of maternal effects. Feminized and masculinized females differ in several traits, including morphological, physiological, behavioural and reproductive traits. Differences previously reported in reproductive traits between feminized and masculinized females come mostly from mechanistic studies performed in the laboratory, and not necessarily on social species. As a result, it is unclear to what extent these reported differences between female alternative morphotypes materialize in wild, natural populations. We quantified the effect of female alternative morphotype on female reproductive traits in a natural population of Octodon degus, a highly social rodent. We assessed female alternative morphotype through a continuous gradient of anogenital distance. Thus, feminized females were close to the short end of anogenital distance, while masculinized females were close to the long end of this gradient. We also tested the hypothesis that the social environment interacts with female morphotype to influence female reproductive traits. In female degus, only body weight affected litter size, where heavier females weaned more offspring. Masculinized females delivered male-biased litters and weaned heavier offspring. Lastly, masculinized females gave birth later in the breeding season compared to feminized females. Contrary to previous claims, our findings do not support that masculinized females are less fertile than feminized females. Moreover, masculinized females produced heavier, potentially higher quality offspring compared with feminized females.

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Embryonic development of the degu, Octodon degus

Cited by 29 publications

References 11 publications

Skeletogenesis and sequence heterochrony in rodent evolution, with particular emphasis on the African striped mouse, Rhabdomys pumilio (Mammalia)

Skeletogenesis and sequence heterochrony in rodent evolution, with particular emphasis on the African striped mouse, Rhabdomys pumilio (Mammalia)

Foetal meiosis in the testis of the rodent Octodon degus

Masculinized females produce heavier offspring in a group living rodent

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