Three months after fertilization and development of a placenta around the developing fetus, the corpus luteum regresses and forms the corpus albicans. Formed placenta takes over progesterone production (which was the role of corpus luteum) and the corpus luteum degrades into a corpus albicans. The corpus luteum is being broken down by macrophages, in a process called luteolysis. The remains of the corpus albicans may persist as a scar on the ovary.