The study investigates the role of the progesterone receptor (PR) in reproductive functions using a mouse model with a null mutation in the PR gene. The researchers found that while male and female embryos homozygous for the PR mutation developed normally, adult female PR mutant mice exhibited significant reproductive abnormalities. These included an inability to ovulate, uterine hyperplasia and inflammation, limited mammary gland development, and an inability to exhibit sexual behavior. The results suggest that progesterone acts as a pleiotropic coordinator of diverse reproductive events, highlighting its essential role in ensuring species survival. The study also provides insights into the specific functions of progesterone in ovulation, uterine development, mammary gland growth, and sexual behavior.The study investigates the role of the progesterone receptor (PR) in reproductive functions using a mouse model with a null mutation in the PR gene. The researchers found that while male and female embryos homozygous for the PR mutation developed normally, adult female PR mutant mice exhibited significant reproductive abnormalities. These included an inability to ovulate, uterine hyperplasia and inflammation, limited mammary gland development, and an inability to exhibit sexual behavior. The results suggest that progesterone acts as a pleiotropic coordinator of diverse reproductive events, highlighting its essential role in ensuring species survival. The study also provides insights into the specific functions of progesterone in ovulation, uterine development, mammary gland growth, and sexual behavior.