Effects of Progesterone on the Uterine Lining. Progesterone plays an important part in the menstrual cycle. The menstrual cycle follows a precise pattern governed by the release of different hormones that interact with one another. Progesterone, whose production increases in the second half of the menstrual cycle, plays a pivotal part in preparing the uterine lining for implantation of an embryo. The corpus luteum, the remains of the ovulating follicle, produces progesterone after ovulation.
The pulmonary artery is the vessel transporting de-oxygenated blood from the right ventricle to the lungs. A common misconception is that all arteries carry oxygen-rich blood. It is more appropriate to classify arteries as vessels carrying blood away from the heart.
The pulmonary artery leaves the right side of the heart and brings blue, deoxygenated blood to the lungs. Occasionally, a child may be born with extra blood vessels that come off of the aorta and travel to the lungs. These are called aortopulmonary (AP) collaterals. They may be present in the setting of other congenital (existing at birth) heart disease. Sometimes the pulmonary artery fails to develop normally and may be too small to take the blue blood to the lungs.