Resolution of corpus luteum occurs because of:

Continued corpus luteum function depends on continued LH production. In the absence of this stimulation, the corpus luteum will invariably regress after 12 to16 days and form scar-like corpora albicans. In the absence of pregnancy, the corpus luteum regresses, and estrogen and progesterone levels wane. If pregnancy occurs, HCG from the placenta will mimic LH action and the corpus luteum continues to secrete progesterone.