increase in ground substance and edema between the stromal cells followed by stromal cell hypertrophy, increased cytoplasmic eosinophilia (predecidual change), and a resurgence of stromal mitoses (see Fig. 22.19C). Predecidual changes spread throughout the functio- nalis and are accompanied by a sparse infiltrate of neutrophils and lymphocytes, which in this context are considered normal. • With the dissolution of the corpus luteum and the subsequent drop in progesterone levels, the functionalis degenerates and bleeding into the stroma occurs, followed by stromal breakdown and onset of the next menstrual cycle