Something to wear to your next estrogen fest! Awesome enamel pin features the molecular structure for estradiol, one of three types of estrogen made by the human body. Estrogen is a hormone that regulates the menstrual cycle, pregnancy and secondary female sex characteristics such as breasts and wide hips. Egg follicles inside the ovary make estrogen, which goes into your bloodstream. During the menstrual cycle, estrogen triggers ovulation and helps build up the uterine walls. Soft enamel zinc alloy pin measures 1.25" tall and was made in China.