"The early production of progesterone was extremely complex and laborious and the resulting product prohibitively expensive. Butenandt required a ton of cholesterol, obtained from the brains and spinal cords of cattle and the grease from sheep's wool, to obtain 20 lbs of starting material from which commercial quantities of progesterone could be produced. Progesterone, when available, was quoted at $l,000/gm. What opened the door for the development of the pill were two advances in steroid chemistry: the introduction of a new technique that changed progesterone from an expensive rarity to the cheapest of all steroid hormones, and the subsequent modification of the progesterone molecule to make it effective orally."