Final answer:
The corpus luteum degenerates into the corpus albicans if pregnancy does not occur during the menstrual cycle.
Step-by-step explanation:
If pregnancy does not occur during the menstrual cycle, the corpus luteum involutes and becomes the corpus albicans. The corpus albicans is a nonfunctional "whitish body" that will disintegrate in the ovary over a period of several months. During this time, with reduced levels of progesterone, the Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) are again stimulated, and a new cohort of early tertiary follicles starts to grow and secrete estrogen, marking the beginning of a new menstrual cycle.