Practice question

Thermotaxis describes directed movement of capacitated sperm toward warmer temperatures. In female tract temperature rises from cooler sperm reservoir in isthmus toward warmer fertilization site in ampulla after ovulation, creating gradient approximately two degrees. Sperm sense this via thermosensitive TRP channels and opsin-mediated signaling triggering calcium influx that modulates flagellar curvature biasing direction up gradient. Behavior requires capacitation and functional CatSper. By moving toward heat, sperm efficiently ascend tract narrowing search area, complementing rheotaxis and chemotaxis for locating ovulated oocyte within limited viable window, enhancing fertility, conception success and fertilization efficiency.