This is the period wherein, under the influence of estrogen, produced by the granulosa cells of the developing ovarian follicle, the basalis portion of the endometrium undergoes extreme rapid growth of both glands and stroma.
 Proliferative phase endometrium.png
Proliferative phase endometrium.png1. Round to tubular endometrial glands
2. Compact stroma consisting of cells having scant cytoplasm and spindle shaped nuclei
Proliferative phase endometrium