Human Oviduct and Endometrium: Changes over the Menstrual Cycle Chapter 24 Human Oviduct and Endometrium: Changes over the Menstrual Cycle © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition

FIGURE 24.1 Anatomic regions of the human fallopian tube. © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition

FIGURE 24. 2 Cross-section of human fallopian tube, ampulla FIGURE 24.2 Cross-section of human fallopian tube, ampulla. This figure is reproduced in color in the color plate section. Inner mucosa (A) is arranged in longitudinal folds within the middle muscularis (B) and outer serosa (C). The mucosa is lined by a single layer of epithelium (lower panel) composed of ciliated and secretory (nonciliated) cell types. Hematoxylin and eosin (H & E) stain, magnification 20–400×. Source: Images courtesy of Ramya Massand and Jason Moss. © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition

FIGURE 24. 3 Anatomic regions of the human uterus (upper) FIGURE 24.3 Anatomic regions of the human uterus (upper). Cross-section of human endometrium (lower). © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition

FIGURE 24.4 Human endometrium from proliferative (upper), early-secretory (middle), and late-secretory phases (lower). This figure is reproduced in color in the color plate section. Note the wide spacing between simple-appearing glands (proliferative), apically displaced nuclei in the glandular epithelium due to glycogen accumulation (middle), and tortuous glands with secretions and a decidualized stroma with abundant pale cytoplasm (lower). H&E stain, magnification 100–200× (Images courtesy of Ramya Massand and Jason Moss). © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition

FIGURE 24.5 Human endometrial stromal cells in vitro before (A) and after 6 days of treatment with estradiol, medroxyprogesterone acetate, and cAMP (B). Note the plump, rounded cell morphology with enlarged nuclei in the decidualized cells. © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition

FIGURE 24.6 Estrogen and progesterone receptor signaling pathways in the murine endometrium. The early postovulatory phase (Days 0–1.5) is dominated by follicular estradiol (E2) acting via estrogen receptor (ESR) and driving epithelial proliferation (via stromal ESR and downstream growth factors) and the expression of epithelial ESR target genes such as Muc1. At Day 2.5, the epithelium is still proliferating, and progesterone receptor (PGR) is expressed in the uterine epithelium. Indian hedgehog (Ihh), a major PGR target gene, is expressed in the uterine epithelium but acts in paracrine fashion in the stroma, where it binds its receptor (PTCH), which then relieves smoothened (SMO) from repression. By Day 3.5, PGR, in part regulated by NR2F2 (COUP-TFII), is acting to inhibit proliferation of the epithelium, accomplished by both epithelial expression of KLF15 and stromal activation of HAND2, while inducing proliferation of the underlying stroma. Lif, an ESR target gene necessary for blastocyst implantation, is expressed in the glandular epithelium. LIF secreted from the glandular epithelium acts via its receptor, LIFR/ GP130, in the luminal epithelium. With invasion of the blastocyst through the epithelium at Day 4.5, LIF expression shifts into stromal cells surrounding the implanting blastocyst and acts through the transcription factor, STAT3. COX2, a key enzyme in prostaglandin synthesis, is induced through a pathway involving the epithelial sodium channel, ENaC, and emerges as one of the first markers of stromal decidualization. In the stroma, expression of key regulators of decidualization increase robustly from basal levels observed at the time of implantation, concurrent with the wave of stromal cell differentiation (Decidua). © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition