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).
By Dr Ananya Mandal, MD. Sperm is the male reproductive cell in vertebrates. The term is derived from the Greek word sperma meaning seed. Sperm were first observed under a microscope in 1677 by Antonie van Leeuwenhoek who described them as little animals or animalcules.here is little cytoplasm in sperm and the head is densely packed with DNA. Sperm is released from the male in a fluid called semen. Semen is alkaline and does not allow the sperm to be completely motile until they reach the female reproductive tract or the vagina which is acidic in pH.