Figure 4c. Sagittal T2-weighted MR images demonstrate uterine morphologic changes according to age and intrinsic or exogenous sex hormones. (a) Image of the uterus obtained during the reproductive period (in a 24-year-old woman) shows that the uterus is 6-9 cm in length and the cervix is smaller than the corpus. There are three zones: an innermost zone of high signal intensity, a middle zone of low signal intensity, and an outermost zone of intermediate signal intensity. These zones correspond to the endometrium, junctional zone, and outer myometrium, respectively. (b, c) MR images of the uterus obtained during childhood (in a 3-year-old girl) (b) and after menopause (in a 65-year-old woman) (c) show that the uterus is small and the zonal anatomy is indistinct (arrows in b). (d) MR image obtained during the reproductive period (in a 34-year-old woman) after the administration of oral contraceptives. The outer myometrium is thicker and brighter, and the junctional zone and the endometrium are thinner. (e) MR image obtained after the administration of a gonadotropin-releasing hormone analogue in a 36-year-old woman with an endometriotic cyst of the ovary (arrow) and adenomyosis. The gonadotropin-releasing hormone analogue caused a hypoestrogenic state and resulted in marked atrophy of the endometrium and an alteration in myometrial signal intensity (arrowheads).