Some gases are lighter than air. Hydrogen is the lightest of all, and easily manufactured, even at home -- for example by dropping aluminium foil into a solution of sodium hydroxide (highly dangerous because it will spit droplets of hot caustic liquid at you which may blind you permanently if they land in your eyes).
The corpus luteum is essential for establishing and maintaining pregnancy in females. The corpus luteum secretes progesterone, which is a steroid hormone responsible for the decidualization of the endometrium (its development) and maintenance, respectively. It also produces relaxin, a hormone responsible for softening of the pubic symphysis which helps in parturition.
Endometrin is a vaginal insert (suppository) Endometrin is a vaginal insert containing progesterone 100mg. Progesterone is a female hormone important for ovulation and menstruation, it is often used as an IVF drug or as part of an assisted fertility drug program. Progesterone causes changes in the lining of the uterus, making it easier for a fertilized egg to attach to the uterus at the beginning of pregnancy.