Sperm competition is a potent mechanism of postcopulatory sexual selection that has been found to shape reproductive morphologies and behaviours in promiscuous animals. Especially sperm size has been argued to evolve in response to sperm competition through its effect on sperm longevity, sperm motility, the ability to displace competing sperm, and ultimately fertilization success. Additionally, sperm size has been observed to co-evolve with female reproductive morphology. Theoretical work predicts that sperm competition may select for longer sperm but may also favour shorter sperm if sperm size trades-off with number. In this study, we studied the relationship between sperm size and postmating success in the free-living flatworm, Macrostomum lignano. Specifically, we used inbred isolines of M. lignano that varied in sperm size to investigate how sperm size translated into the ability of worms to transfer and deposit sperm in a mating partner. Our results revealed a hump-shaped relationship with individuals producing sperm of intermediate size having the highest sperm competitiveness. This finding broadens our understanding of the evolution of sperm morphology by providing empirical support for stabilizing selection on sperm size under sperm competition.
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http://dx.doi.org/10.1093/jeb/voae058 | DOI Listing |
Hum Reprod
January 2025
IRSD, Université de Toulouse, INSERM, INRAE, ENVT, Univ Toulouse III-Paul Sabatier (UPS), Toulouse, France.
Study Question: Does a human fallopian tube (HFT) organoid model offer a favourable apical environment for human sperm survival and motility?
Summary Answer: After differentiation, the apical compartment of a new HFT organoid model provides a favourable environment for sperm motility, which is better than commercial media.
What Is Known Already: HFTs are the site of major events that are crucial for achieving an ongoing pregnancy, such as gamete survival and competence, fertilization steps, and preimplantation embryo development. In order to better understand the tubal physiology and tubal factors involved in these reproductive functions, and to improve still suboptimal in vitro conditions for gamete preparation and embryo culture during IVF, we sought to develop an HFT organoid model from isolated adult stem cells to allow spermatozoa co-culture in the apical compartment.
Naunyn Schmiedebergs Arch Pharmacol
January 2025
Department of Pathology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, 22758, Egypt.
This study investigates the protective effects of resveratrol (RSV) against heat stress (HS)-induced testicular injury in rats. Climate change has exacerbated heat stress, particularly affecting male fertility by impairing testicular function and sexual behavior. A total of 32 rats were allocated into four experimental groups: control, RSV control, HS control, and RSV + HS.
View Article and Find Full Text PDFInt J Pharm
January 2025
Department of Industrial Pharmacy, College of Pharmaceutical Sciences and Drug Manufacturing, Misr University for Science and Technology, Giza, Egypt. Electronic address:
Clotrimazole (CLO) is a strong antifungal drug approved to treat vaginal candidiasis (VC). Nanosponges (NSs) were developed to maintain providing CLO in a steady pattern with amplified accumulation in the vaginal mucosa. The quasi-emulsion solvent diffusion method was utilized to prepare NSs.
View Article and Find Full Text PDFR Soc Open Sci
January 2025
Laboratory of Animal Sociology, Department of Biology, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan.
In animals where males engage in multiple matings, sperm depletion can substantially reduce the reproductive success of both sexes. However, little is known about how successive matings affect sperm depletion, fertilization rates and mating behaviour. Here, we investigated this phenomenon under laboratory conditions.
View Article and Find Full Text PDFAnat Rec (Hoboken)
January 2025
Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, USA.
The pygmy sperm whale (Kogia breviceps) possesses an exocrine gland associated with its false gill slit pigmentation pattern. The cervical gill slit gland is a compound tubuloalveolar gland that produces a holocrine secretion and displays maturational changes in size and secretory histology. While the morphology of the cervical gill slit gland has been described in detail, to date, the chemical composition of its secretion remains uncharacterized.
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