Table 1. Ca²⁺ Dependency on the Occurrence Rate of the Oscillatory Microtubule Sliding Movement.

Ca2+ concentration (M)	10−5	10−7	10−8	10−9
Occurrence rate (%)	2.2 ± 1.1 (1946, 6)	2.8 ± 1.4 (1087, 5)	5.4 ± 1.8 (638, 5)	8.1 ± 3.5 (339, 6)

Data are presented as mean ± s.d. Numbers in parentheses represent the total sperm scored and the number of experiments performed. Significant differences were found between values at different Ca²⁺ concentrations except between 10⁻⁵ and 10⁻⁷ M.