spermatogenezaseminiferous tubule (human)

The ovum, or egg, in a woman forms as a result of the inward spiral motion of follicles in the ovaries, while the sperm in a man is due to the outward differentiation of reproductive cells. These processes are, respectively, yang and yin; fusing, they create new life.
Michio Kushi form “The Macrobiotic Path to Total Health”