Overview

• The CatSper ion channel, exclusive to mammalian sperm, activates at temperatures around 38°C, aligning with the female reproductive tract's warmth to trigger hyperactive motility required for fertilization.
• Knockout experiments in mice confirmed CatSper as the primary temperature sensor, with sperm lacking the channel showing no heat-induced calcium influx.
• Mammalian testes evolved external positioning to maintain cooler temperatures, preventing premature CatSper activation and preserving sperm viability until ejaculation.
• Protective mechanisms, such as acidic epididymal conditions and spermine in seminal fluid, inhibit premature CatSper activation until sperm reach the female reproductive tract.
• The findings suggest potential for non-hormonal male contraceptives and infertility treatments by targeting CatSper activation through temperature manipulation.