Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Schematic comparison of the 4-day rodent reproductive cycle and the 28-day human menstrual cycle. Depicted are average fluctuations of the circulating hormones 17-beta-estradiol, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) in a female rat (left panel) vs. a female human (right panel). Gray bars in the left panel depict the dark phases. Data for individual hormones were adapted from [120, 339, 353]
