Figure 9.
Histologic sections of developing human uterine tubes. (A) Transverse section of that portion of an 8-week Müllerian duct destined to form the uterine tube. At this early stage the uterine tube consists of an undifferentiated simple columnar epithelium surrounded by loose mesenchyme. By 14 weeks, epithelial morphology of the isthmus (B), ampulla (C) and infundibulum (D) is more complex, and the stroma surrounding the epithelium is densely cellular (B–D). By the 18th week (E & F) the ampullary mesenchyme has differentiated into a condensed stromal layer (doubled-headed black arrows) associated with the epithelium and a surrounding circularly oriented layer (green double-headed arrows) that has differentiated into α-actin-reactive smooth muscle (F). (A–E) = H&E, (F) = α-actin.