What hormone surge causes ovulation during the menstrual cycle?

The surge in luteinizing hormone (LH) is the key event that triggers ovulation during the menstrual cycle. Midway through the cycle, there is a significant rise in estrogen levels produced by the developing follicles, which in turn stimulates a dramatic increase in LH. This LH surge leads to the completion of the first meiotic division of the oocyte and ultimately causes the mature follicle to rupture, releasing the egg into the fallopian tube.

This process typically occurs around day 14 of a 28-day cycle and is essential for fertility, as it is the moment when fertilization can take place. LH also plays a role in the subsequent formation of the corpus luteum, which produces progesterone to help prepare the uterine lining for potential implantation. Understanding the role of LH is crucial for grasping the complexities of the hormonal feedback mechanisms governing the menstrual cycle and ovulation.