Each month, the uterus undergoes a menstrual phase if pregnancy fails to occur.
During the menstrual phase the endometrium is shed along with bleeding that occurs due to the rupture of the endometrial blood vessels.
The proliferative phase lasts for about nine days.
It is during this phase that the endometrium thickens.
The secretory phase follows ovulation, and it is during this phase that the glands of the uterus make glycoproteins that serve as embryonic nutrition prior to implantation.
The secretory phase is approximately 13 days long.
