Postcopulatory sexual selection leads to an increase in sperm numbers which is partly the result of an increase in relative testes mass and could also be the consequence of changes in testis architecture or function. Very little is known regarding developmental changes during the first spermatogenic wave that may lead to enhanced spermatogenic efficiency and increased sperm production. We examined testicular development after birth in four mouse species with different sperm competition levels to assess changes in testicular architecture and function. Differences in relative testes mass between species appeared soon after birth and were exacerbated thereafter. The volume of testes occupied by seminiferous tubules differed between species postnatally and were associated with sperm competition levels. Finally, changes over time in the proportions of tubules with different germ cell types were also associated with sperm competition levels, with the time taken for the transition between various cell stages being negatively associated with levels of sperm competition. We conclude that postnatal testis development differs between closely related species with different sperm competition levels influencing testis architecture and the rate of progression of spermatogenesis, leading to differences in testis function at reproductive maturity.
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http://dx.doi.org/10.1530/REP-11-0245 | DOI Listing |
Sci Rep
January 2025
Centre for Ecology and Conservation, Faculty of Environment, Science & Economy, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, UK.
Promiscuous females reduce male reproductive control. Males can attempt to monopolise access to these females, but distractions and sneaky rivals mean extra copulations cannot always be blocked. By mating first, males can obtain a headstart in sperm competition, but this may be negated by sperm storage and cryptic female choice mechanisms.
View Article and Find Full Text PDFJ Comp Physiol A Neuroethol Sens Neural Behav Physiol
January 2025
Laboratorio de Investigaciones Ecoetológicas de Moscas de la Fruta y sus Enemigos Naturales (LIEMEN), División Control Biológico de Plagas, PROIMI-Biotecnología, CONICET, Avenida Belgrano y Pasaje Caseros s/n, San Miguel de Tucumán, Tucumán, 4000, Argentina.
During copulation male insects transfer sperm and seminal fluids, including accessory gland proteins (Acps) to females, produced in the accessory glands (AGs). These Acps influence female behavior and physiology, inhibiting sexual receptivity, promoting ovulation and/or oviposition. The theory of ejaculate allocation postulates that production is costly; therefore, males strategically allocate ejaculates based on perception of sperm competition and quality and availability of females.
View Article and Find Full Text PDFProc Biol Sci
January 2025
Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, Australia.
Sperm are traditionally viewed as transcriptionally and translationally silent cells. However, observations that components of the cellular machinery of gene expression are maintained in ejaculated sperm are increasingly cited as challenges to this fundamental assumption. Here, we critically evaluate these arguments and present three lines of evidence from both model and non-model systems that collectively raise the question of whether ejaculated sperm may be capable of active gene expression.
View Article and Find Full Text PDFbioRxiv
December 2024
Department of Integrative Biology, Oklahoma State University, Stillwater OK 74078 USA.
Social circuitry of the mammalian brain can influence male reproductive physiology. This often manifests as plasticity in sperm production or allocation, particularly in response to male-male competition. However, socially mediated testicular plasticity has not been investigated with respect to mating and parental strategy.
View Article and Find Full Text PDFJ Endocr Soc
November 2024
Division of Endocrinology, Metabolism and Diabetes, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA.
"Pseudo-endocrine disorders" refer to proposed conditions that have never been scientifically proven to exist but, due to widespread misinformation available on the internet and other media, are relatively commonly diagnosed and treated with equally unproven and sometimes dangerous treatments. Adrenal fatigue is a nonexistent condition that supposedly results from adrenal exhaustion and atrophy due to chronic stress and has been promoted as a potential explanation for a variety of symptoms. Testing consists of nonvalidated online surveys and salivary cortisol profiles while treatment is not evidence-based at best and can be dangerous.
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