Description
The transition of regularly cycling endometrium from the proliferative or Estrogen-dominant phase of the menstrual cycle to the Progesterone-dominant Early and Mid Secretory phases requires wide-spread changes in gene expression that shift the endometrium from a proliferative capacity to a differentiated 'decidual' phenotype in preparation for implantation. This process appears delayed in women with severe endometriosis, suggestive of a progesterone resistant endometrium in this disease.