Vitiligo Definition and Overview. Vitiligo is an autoimmune skin disease in which there is a progressive destruction of the skinâs pigment-producing cells (melanocytes), resulting in areas of otherwise normal white skin devoid of melanin pigment. It is not unusual for hairs growing in areas of vitiligo to lose their normal color.
Sperm Cycle. Old sperm cells die off and new cells are created at a rate of about one percent each day. This means the entire sperm cycle requires approximately 100 days. The final 75 days represent a period of maturation for the sperm cell. This final step of sperm maturation, called spermiogenesis, puts the fuel into the tank and completes the development of the sperm cell (spermatozoon).
A male who has reached puberty will produce millions of sperm cells every day. Each sperm is extremely small: only 1/600 of an inch (0.05 millimeters long). Sperm develop in the testicles within a system of tiny tubes called the seminiferous tubules.