Ovulation its lifespan. Without the oocyte, the follicle folds inward on itself, transforming into the corpus luteum (pl. corpora lutea), a steroidogenic cluster of cells that produces estrogen and progesterone. These hormones induce the endometrial glands to begin production of the proliferative endometrium and later into secretory endometrium, the site of embryonic growth if implantation occurs. The action of progesterone increases basal body temperature by one-quarter to one-half degree Celsius (one-half to one degree Fahrenheit). The corpus luteum continues this paracrine action for the remainder of the menstrual cycle, maintaining the endometrium, before disintegrating into scar tissue during menses. The start
Pharmacokinetics of progesterone and has been found to result in higher serum peak progesterone levels relative to intramuscular oil formulations. In addition, subcutaneous injection of progesterone is considered to be easier, safer (less risk of injection site reactions), and less painful relative to intramuscular injection. The elimination half-life of this formulation is 13 to 18 hours, compared to 20 to 28 hours for intramuscular injection in oil. Progesterone has a very short elimination half-life of about 3 to 90 minutes when given by intravenous injection. A one-year progesterone intrauterine device (IUD) for hormonal birth control was previously available in the United States and