Ultrastructural study reveals paternal inheritance and replication of sperm centrioles in human embryos, highlighting the paternal origin of human somatic centrosomes.
Key Points
To determine the inheritance pattern, replication process, and continuity of paternal sperm centrioles during early human embryonic development.
Examined monospermic and abnormal dispermic human embryos (n = 127) using transmission electron microscopy.
Tracked centriole ultrastructure and spindle associations from post-fertilization pronuclear formation through the hatching blastocyst stage.
The paternal proximal centriole enters the oocyte at fertilization, duplicates at the pronuclear stage to generate a sperm aster, and occupies opposite spindle poles at syngamy.
Replication occurs via perpendicular lateral growth of daughter centrioles surrounded by electron-dense pericentriolar material, persisting through the 1-cell, cleavage, and blastocyst stages across trophoblast, embryoblast, and endoderm lineages.
Dispermic embryos exhibited abnormal spindle geometries, including tripolar spindles in four embryos with accessory centrioles, confirming the functional activity of paternal centrosomes.