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Effects of seminal vesicle fluid components on sperm motility in the house mouse
1Biology Department, California State University-Los Angeles 90032.
Abstract:
Fluid obtained by stripping dissected seminal vesicles was mixed with phosphate-buffered saline and the soluble proteins were separated by gel filtration on BioRad P150 into 4 fractions. Fractions were collected and concentrated using an Amicon ultrafiltration system using YM2 membranes with a molecular weight cut-off of 1000. Epididymal sperm suspensions were incubated in medium containing one of the 4 fractions or 1 mg BSA/ml, or no added protein. After incubation for 2 h the motility of the spermatozoa in each suspension was assessed by a videomicrographic procedure. Two aspects of motility, velocity and the shape of the swimming path, were monitored. The results indicate that the seminal vesicles produce at least three factors that influence sperm motility. Fraction 3 (Mr 12,000-24,000) was detrimental to motility; after incubation for 2 h almost all the spermatozoa were immotile. Fractions 2 (Mr 25,000-40,000) and 4 (Mr 7000-12,000) both influenced the shape of the swimming path: spermatozoa incubated in Fraction 2 had straighter trajectories while those incubated in Fraction 4 showed more progressive paths with less side-to-side movement of the head about the path. These effects of factors from the seminal vesicle fluid on sperm motility may influence the way in which the spermatozoa move in the female reproductive tract and could help to explain why removal of the seminal vesicles reduces fertility in the mouse.
Insights
Seminal vesicles secrete factors influencing sperm motility. While one fraction impairs movement, others alter sperm swimming paths, potentially impacting fertility.
Area of Science:
- Reproductive Biology
- Sperm Physiology
- Mammalian Reproduction
Background:
- Seminal vesicles contribute fluid to semen, but their specific roles in modulating sperm function remain incompletely understood.
- Sperm motility is crucial for fertilization, and external factors can significantly influence its parameters.
Purpose of the Study:
- To investigate the effects of seminal vesicle fluid proteins on sperm motility.
- To identify specific protein fractions from seminal vesicles that modulate sperm velocity and swimming path characteristics.
Main Methods:
- Proteins from seminal vesicle fluid were isolated and separated into four molecular weight fractions using gel filtration.
- Epididymal sperm were incubated with these fractions, and motility was assessed using videomicrography.
- Key motility parameters, including velocity and swimming path shape, were analyzed.
Main Results:
- One protein fraction (Mr 12,000-24,000) significantly reduced sperm motility, rendering most spermatozoa immotile.
- Two other fractions (Mr 25,000-40,000 and Mr 7000-12,000) differentially affected sperm swimming paths.
- Fraction 2 promoted straighter trajectories, while Fraction 4 resulted in more progressive paths with reduced head movement.
Conclusions:
- Seminal vesicles produce multiple factors that actively regulate sperm motility and behavior.
- These seminal vesicle-derived factors may play a role in sperm navigation within the female reproductive tract.
- The identified modulatory effects could help explain the reduced fertility observed after seminal vesicle removal.