Zona-opening of hamster oocytes: a comparative study using macro- and micro-manipulation methods

Area of Science:

• Reproductive Biology
• Assisted Reproductive Technology
• Gamete Manipulation

Background:

• Zona-opening is a crucial step in some assisted reproductive technologies.
• Conventional micro-manipulation techniques are effective but can be technically demanding.
• Evaluating novel, potentially simpler, techniques is important for advancing fertility treatments.

Purpose of the Study:

• To compare the efficacy of a novel macro-manipulation technique for zona-opening of hamster oocytes against established micro-manipulation methods.
• To assess sperm penetration and polyspermia rates following zona-opening by different techniques.

Main Methods:

• Experiment I: Hamster oocytes underwent zona-opening using a 32-gauge steel needle (macro-manipulation) and were co-incubated with human spermatozoa. Controls included zona-free and zona-intact oocytes.
• Experiment II: Oocytes were zona-opened via macro- or micro-manipulation and co-incubated with human spermatozoa.
• Sperm penetration and polyspermia rates were evaluated in all groups.

Main Results:

• In Experiment I, 26% of oocytes lysed after macro-manipulation. Sperm penetration was 37% for zona-opened and 60% for zona-free oocytes.
• Polyspermia rates were 12% and 28% for zona-opened and zona-free oocytes, respectively.
• In Experiment II, lysis rates were comparable (6% macro vs. 8% micro). Penetration (55% macro vs. 64% micro) and polyspermia rates (30% macro vs. 37% micro) were not significantly different between macro- and micro-manipulation techniques.

Conclusions:

• Macro-manipulation for zona-opening of hamster oocytes results in similar sperm penetration and polyspermia rates compared to conventional micro-manipulation.
• The macro-manipulation technique presents a viable alternative, potentially offering a simpler approach for zona-opening in assisted reproduction.