title: The mechanics clarifying counterclockwise rotation in most IVF eggs in mice.
abstract: In mammalian fertilization, a small spermatozoon interacts with an egg that is a few thousand times larger in volume. In spite of the big difference in size and mass, when spermatozoa are bound to eggs, they begin rotating the eggs in in vitro observation. This was dubbed the 'fertilization dance'. Interestingly, some papers reported that the rotation was counterclockwise, although the reason for this skewed rotation was not clarified. We focused on a chirality of helical beating of spermatozoa and found that eggs rotate counterclockwise in simulations under a certain geometrical condition where the eggs were situated. This theory of egg rotation was validated by demonstrating egg rotation in a clockwise direction by floating eggs to the upper surface of the IVF medium. The enigma of skewed rotation of IVF eggs was clarified.
authors.affiliation: The Hakubi Center for Advanced Research, Kyoto University, Kyoto, Japan.|Research Institute for Mathematical Sciences, Kyoto University, Kyoto, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Ishimoto
authors.affiliation: Research Institute for Microbial Diseases, Osaka University, Suita, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Ikawa
authors.affiliation: Research Institute for Microbial Diseases, Osaka University, Suita, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Okabe
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D005260:Female; D005307:Fertilization in Vitro; D008297:Male; D051379:Mice; D010063:Ovum / Q000502:physiology* / Q000648:ultrastructure; D012399:Rotation; D013094:Spermatozoa / Q000502:physiology* / Q000648:ultrastructure