Interaction of semen with ova in vitro

Area of Science:

• Reproductive biology
• Biochemistry

Background:

• Spermine is a polyamine found in seminal plasma.
• Its role in mammalian fertilization is complex and not fully understood.
• Bovine serum albumin (BSA) is commonly used in in vitro fertilization (IVF) media.

Purpose of the Study:

• To investigate the direct effects of spermine and seminal plasma on mammalian fertilization.
• To identify factors in incubation media that may interfere with these effects.
• To assess the role of spermine oxidase in spermine's impact on fertilization.

Main Methods:

• In vitro fertilization assays using zona-free mouse ova.
• Incubation of gametes with varying concentrations of spermine and seminal plasma.
• Use of untreated and TCA-purified BSA in incubation media.
• Assay for spermine oxidase activity.
• Addition of isoniazid, a spermine oxidase inhibitor.

Main Results:

• Spermine positively influenced fertilization of zona-free mouse ova in vitro.
• Detrimental effects of spermine or seminal plasma on gametes were observed only with untreated BSA.
• Spermine oxidase activity was detected in untreated BSA and responsible for the deleterious effects.
• TCA-purification of BSA removed spermine oxidase activity.
• Isoniazid inhibited spermine oxidase, mitigating negative effects.
• Human seminal plasma impaired human and mouse sperm fertilizing ability, but only when capacitation was not pre-induced.

Conclusions:

• The presence of spermine oxidase in untreated BSA can mask the true effects of spermine and seminal plasma on fertilization.
• TCA-purified BSA or spermine oxidase inhibitors like isoniazid are necessary for accurate assessment of spermine and seminal plasma's direct impact.
• Human seminal plasma negatively affects sperm capacitation and fertilizing ability, particularly in mouse spermatozoa.