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Sperm integrity is critical for normal mitotic division and early embryonic development
M Moomjy1, L T Colombero, L L Veeck
1The Center For Reproductive Medicine and Infertility, Department of Obstetrics and Gynecology, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, New York 10021, USA.
Molecular Human Reproduction
|August 25, 1999
Summary
Spermatozoa integrity is crucial for normal embryonic development. Dissected spermatozoa can initiate fertilization and cleavage but lead to abnormal mitotic divisions and chromosomal mosaicism in human zygotes.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Cell Biology
Background:
- The centrosome, essential for the first mitotic division of the human zygote, is provided by the paternal gamete.
- It remains unclear if an intact spermatozoon is necessary for normal centrosome function or if isolated components suffice.
Purpose of the Study:
- To investigate the impact of sperm integrity on centrosome function and subsequent embryonic development in human oocytes.
- To determine if dissected spermatozoa can support normal zygote formation and embryonic progression.
Main Methods:
- Mature human oocytes were microinjected with either intact or mechanically-dissected spermatozoa.
- Fertilization, cleavage rates, nuclear/cytoskeletal changes (fluorescent immunocytochemistry), and chromosomal normality (fluorescent in-situ hybridization) were assessed.
- A pilot study identified cytoskeletal landmarks of centrosome function.
Main Results:
- Oocytes injected with dissected spermatozoa achieved pronuclear formation and cleavage but failed normal mitotic division.
- No bipolar spindle formation was observed in zygotes derived from dissected sperm injections.
- Chromosomal mosaicism was prevalent in embryos resulting from dissected sperm injections.
Conclusions:
- Impaired sperm integrity following dissection disrupts the formation of the bipolar spindle, a critical component of the mitotic apparatus.
- This disruption leads to chromosomal abnormalities and suggests that intact spermatozoa are required for normal human embryonic development.