Muroid Copulatory Plugs and Female Reproductive Tracts: A Comparative Investigation

Baumgardner, Denis J.; Hartung, Thomas G.; Sawrey, D. Kim; Webster, Daniel G.; Dewsbury, Donald A.

doi:10.2307/1380677

Cited by 32 publications

(23 citation statements)

References 14 publications

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“…Controlling for variation in female vaginal length, there was also a significant correlation between relative testis size and plug length (nZ12, partial rZ0.65, tZ2.54, pZ0.03, lZ0). Similarly, holding relative testis size constant revealed a significant correlation between vaginal length and plug length (nZ12, partial rZ0.84, tZ4.63, pZ0.001, lZ0), as reported by Baumgardner et al (1982).…”

Section: (B) Accessory Gland Sizesupporting

confidence: 57%

“…(d) Copulatory plug size To investigate variation in copulatory plug size among rodents, data on plug size were taken from Hartung & Dewsbury (1978) and Baumgardner et al (1982). The latter of these studies found a correlation between plug length and vaginal length, and vaginal length was therefore also included in the analysis.…”

Section: Materials and Methods (A) Comparative Analysesmentioning

confidence: 99%

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Sperm competition and the evolution of male reproductive anatomy in rodents

2005

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Sperm competition is a pervasive selective force in evolution, shaping reproductive anatomy, physiology and behaviour. Here, we present comparative evidence that varying sperm competition levels account for variation in the male reproductive anatomy of rodents, the largest and most diverse mammalian order. We focus on the sperm-producing testes and the accessory reproductive glands, which produce the seminal fluid fraction of the ejaculate. We demonstrate a positive association between relative testis size and the prevalence of within-litter multiple paternity, consistent with previous analyses in which relative testis size has been found to correlate with sperm competition levels inferred from social organization and mating systems. We further demonstrate an association between sperm competition level and the relative size of at least two accessory reproductive glands: the seminal vesicles and anterior prostate. The size of the major product of these glands-the copulatory plug-is also found to vary with sperm competition level. Our findings thus suggest that selection for larger plugs under sperm competition may explain variation in accessory gland size, and highlight the need to consider both sperm and non-sperm components of the male ejaculate in the context of post-copulatory sexual selection.

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Section: (B) Accessory Gland Sizesupporting

confidence: 57%

Section: Materials and Methods (A) Comparative Analysesmentioning

confidence: 99%

Sperm competition and the evolution of male reproductive anatomy in rodents

2005

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“…Expulsion of plugs apparently was facilitated by exfoliation of the superficial, cornified vaginal epithelium, as reported for some other rodents (Voss 1979). Whereas the copulatory plugs of some rodents terminate anteriorly in a broad end forming a cup against the cervix (Baumgardner et al 1982;Hartung and Dewsbury 1978;Matthews and Adler 1977), the plugs of Richardson's ground squirrels tapered toward the cervix.…”

Section: Discussionmentioning

confidence: 99%

“…Murie and McLean (1980) reported that they were unable to detect plugs in three Columbian ground squirrels inspected 3-4 h after a presumed underground copulation whereas those females had detectable plugs the next day. In muroid rodents, plugs form within 15 min of ejaculation but are not always noticeable during external examination (Baumgardner et al 1982;Hartung and Dewsbury 1978). The acellular and almost aspermic composition of the core of the copulatory plug in Richardson's ground squirrels suggests that the core results from a rapidly congealing fraction of seminal fluid that is ejaculated after the sperm mass, as in rats (Matthews and Adler 1977).…”

Section: Discussionmentioning

confidence: 99%

“…Although copulatory plugs, coagulated ejaculate located in the vaginae of recently inseminated females, result from copulations in many species of murid and cricetid rodents (Baumgardner et al 1982;Hartung and Dewsbury 1978;Voss 1979), such plugs are reported infrequently for sciurid rodents. Among ground squirrels (genus Spermophilus), copulatory plugs have been recorded for S. triciec*emlineutus (Foster 1934;Simmons I 946).…”

Section: Introductionmentioning

confidence: 99%

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Copulatory plugs in Richardson's ground squirrels

Michener¹

1984

Can. J. Zool.

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The frequency with which copulatory plugs, coagulated ejaculate located in the vaginae of recently inseminated females, occur in Richardson's ground squirrels was determined during a 4-year study. In each year, on average, 37% of females captured on 3 consecutive days centered on the time of mating had a copulatory plug. Plugs filled the vaginal lumen, firmly adhered to the vaginal wall, sometimes remained in place as long as 15 – 17 h, and were expelled via sloughing of the vaginal epithelium. The function(s) of copulatory plugs could not be determined in this study, but protection of the male's sperm investment and prevention of sperm leakage were potential consequences of plug formation.

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Sexual dimorphism and hormone responsiveness in the spinal cord of the socially monogamous prairie vole (Microtus ochrogaster)

Holmes

Musa

Lonstein

et al. 2009

J of Comparative Neurology

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Prairie voles (Microtus ochrogaster) are exceptional among rodents in that many aspects of their brain and behavior are not masculinized by exogenous aromatizable androgens. However, the sexually differentiated endpoints studied to date rely on estrogenic mechanisms in other mammals. We examined whether sexual differentiation of an androgen receptor-dependent sex difference would be similarly distinct in prairie voles. Male mammals have more and larger motoneurons projecting to perineal muscles than do females. This sex difference normally arises from males' perinatal androgen exposure and can be eliminated by treating developing females with androgens. Gross dissection revealed bulbospongiosus muscles in adult male, but not female, prairie voles. Retrograde tracing from males' bulbocavernosus muscles and the external anal sphincter from both sexes revealed sexually dimorphic populations of labeled motoneurons in the ventral horn of the lumbar spinal cord. Similar to other rodents, males had twice as many motoneurons as females, although no sex difference in motoneuron size was detected. Unexpectedly, prenatal or early postnatal exposure to testosterone propionate had no effect on adult females' motoneuron number or size. In adulthood, gonadectomy alone or followed by chronic testosterone treatment also had no effect on females' motoneuron size or number, although castration reduced motoneuron size in males. Comparing gonadally intact weanlings confirmed that the sex difference in motoneuron number exists before adulthood. As with some other sexually dimorphic traits, and perhaps related to their unique social organization, sexual differentiation of the prairie vole spinal cord differs from that found in most other laboratory rodents.

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Muroid Copulatory Plugs and Female Reproductive Tracts: A Comparative Investigation

Cited by 32 publications

References 14 publications

Sperm competition and the evolution of male reproductive anatomy in rodents

Sperm competition and the evolution of male reproductive anatomy in rodents

Copulatory plugs in Richardson's ground squirrels

Sexual dimorphism and hormone responsiveness in the spinal cord of the socially monogamous prairie vole (Microtus ochrogaster)

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