During this phase, mitosis is occurring in both lamina propria stroma and epithelial glands. Note that, early in this phase, the stratum functionalis is relatively thin, and that the epithelium is low columnar. The three strata are most readily identified at this stage. Early in this phase, profuse glandular secretion commences. The stratum basalis remains closely attached to the myometrium.
Coiled arteries constrict intermittently.
They play a major role in the menstrual stage. At this time, the ischemia caused by the constriction of the spiral arteries results in necrosis of the stratum functionalis. This is followed by the shedding of this layer.