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Oocyte activation induced by spermatids and the spermatozoa
K Yanagida1, H Yazawa, H Katayose
1Department of Obstetrics and Gynecology, School of Medicine, Fukushima Medical University, Japan.
International Journal of Andrology
|June 13, 2000
Summary
Sperm factor (SF) initiates oocyte activation and calcium oscillations during fertilization, with abilities developing differently across sperm maturation stages and species. Impaired SF affects ICSI patients, treatable with artificial oocyte activation.
Area of Science:
- Reproductive Biology
- Spermatozoa Research
- Fertilization Mechanisms
Background:
- A sperm factor (SF) in spermatozoa is crucial for fertilization.
- The specific oocyte-activating and calcium oscillation (Ca-Os)-inducing abilities of SF are not fully understood.
Purpose of the Study:
- To investigate the oocyte-activating and Ca-Os-inducing capacities of spermatids and spermatozoa across different species.
- To determine the developmental timing of these abilities during spermiogenesis.
Main Methods:
- Utilized a mouse model by injecting spermatids and spermatozoa from mice, hamsters, and humans into mouse oocytes.
- Assessed oocyte activation rates and observed patterns of Ca-Os (Type A: normal, Type B: abnormal, Type C: none).
Main Results:
- Oocyte activation and Ca-Os induction abilities emerge at distinct spermiogenesis phases, varying by species.
- In mice, round spermatids showed no Ca-Os, while elongated spermatids and spermatozoa induced oscillations.
- Human sperm activated oocytes but showed lower rates of normal Ca-Os compared to mice and hamsters.
Conclusions:
- Oocyte activation typically occurs between round and elongated spermatid stages, but timing varies across species.
- Oocyte activation does not always correlate with Ca-Os, suggesting distinct thresholds or factors for each process.
- Impaired SF was identified in 0.9% of ICSI patients, responsive to artificial oocyte activation combined with ICSI.