Menstrual cycle and the lining of the uterus thickens. Follicles in the ovary begin developing under the influence of a complex interplay of hormones, and after several days one or occasionally two become dominant (non-dominant follicles shrink and die). Approximately mid-cycle, 24–36 hours after the luteinizing hormone (LH) surges, the dominant follicle releases an ovocyte, in an event called ovulation. After ovulation, the ovocyte only lives for 24 hours or less without fertilization while the remains of the dominant follicle in the ovary become a corpus luteum; this body has a primary function of producing large amounts of progesterone. Under the influence
Menstrual synchrony of northwestern California, according to one ethnographic study, "all of a household's fertile women who were not pregnant menstruated at the same time..." The phenomenon of menstrual synchrony is the closeness in time of the menstrual cycle onsets of two or more women. The phenomenon is not synchronization in the strict sense of concordance of menstrual cycle onsets but the term "menstrual synchrony" is still used perhaps misleadingly. As an undergraduate, Martha McClintock published the first study on menstrual synchrony; her report detailed the menstrual synchrony of undergraduate women living in a dormitory in Wellesley College. Since then, there have