Structure of the uterus throughout the ovarian cycle and the cervix. A Structure of the uterus throughout the ovarian cycle and the cervix. A. Basic structure of the wall of the uterus during the secretory phase. B. Levels of pituitary and ovarian hormones and the resulting changes in ovarian follicles and uterine endometrium during a typical 28-day ovarian cycle. C. Section through the wall of the uterus during the menstrual or early proliferative phase of the ovarian cycle. The endometrium consists simply of the basal layer and base of the glands at this stage. Only part of the myometrium is shown. D. Section through the wall of the uterus during the secretory phase of the ovarian cycle. Asterisks indicate the border between the functional (upper) and basal (lower) layers of the endometrium. Only part of the myometrium is shown. Inset shows the spiral arteries (arrows) and a gland (G) at higher magnification. Note the difference in magnification between parts C and D. E. Longitudinal section through the cervix of an adult woman. Regions lined with simple mucus-secreting columnar epithelium are shown in dark pink; regions lined with stratified squamous epithelium are shown in blue. The transformation zone represents the regions in which the epithelium transitions between columnar and squamous during a woman's life. F. Longitudinal section through the lower portion of the cervix near the junction with the vagina. The double arrowhead indicates the opening of a gland into the cervical canal. The inset shows the boxed area containing the squamocolumnar junction at higher magnification. Source: FEMALE REPRODUCTIVE SYSTEM, The Big Picture: Histology Citation: Ash R, Morton DA, Scott SA. The Big Picture: Histology; 2017 Available at: https://accessphysiotherapy.mhmedical.com/DownloadImage.aspx?image=/data/books/2058/ashhist_ch15_f003ef.png&sec=155785016&BookID=2058&ChapterSecID=155784976&imagename= Accessed: December 28, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved