A 26 year old female presents with a chief complaint of menstrual bleeding 10 days prior to the usual onset of menses. She states that her last menstrual period was heavier than usual. The physician examines her and performs a pregnancy test (which is negative) then concludes that she is probably experiencing dysfunctional bleeding due to anovulation. If an endometrial biopsy were performed, which of the following would be the most likely histologic appearance of this type of endometrium?