Final answer:
The proliferative phase is when the endometrial lining of the uterus rebuilds and thickens, stimulated by estrogen, and lasts from day 7 to day 14 of the uterine cycle.
Step-by-step explanation:
Clinical Appearance of the Proliferative Phase
The proliferative phase is the second phase of the uterine cycle, following the menses phase. It is characterized clinically by the rebuilding of the endometrial lining of the uterus, which becomes thicker and more vascular under the influence of estrogen. This hormone is secreted by the maturing ovarian follicles, specifically by the granulosa and theca cells of the tertiary follicles. During this phase, estrogen also stimulates the cervix to secrete a larger amount of thinner mucus, aiding sperm motility and hence increasing the likelihood of fertilization.
The proliferative phase typically ranges from day 7 to day 14 of a 28-day menstrual cycle, marking the period after the end of menstruation when the endometrium begins to proliferate again. This phase aligns with the follicular phase of the ovarian cycle, characterized by slowly rising levels of Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH), which stimulate the growth of ovarian follicles in preparation for ovulation.