Figure 5. Vas deferens (VD) distal (abdominal) to the site of vasectomy in patients undergoing vasectomy reversal as seen in the light microscope (a, b) and electron microscope (c). In the light microscope (a), the VD from a patient having undergone vasectomy 14 years earlier showed a lumen that was indistinct and a convoluted flattened epithelium (E) recognized merely by the presence of the epithelial nuclei (arrows). In (b), the epithelium is reduced to a flattened layer of cells with no discernible lumen. Blood vessels (arrowheads) abound in the area adjacent to the epithelium. Inset: high-power light micrograph of a blood vessel containing red blood corpuscles and neutrophils (curved arrows). The latter are also present in the lamina propria outside the blood vessel (curved arrows). (c) Distal (abdominal) VD from the same patient as in Figure 4, having undergone vasectomy 9 years earlier. At the electron microscopic level, the epithelium is flattened and consists of a layer of principal cells (P) extending from the basement membrane (arrows) toward the lumen and portions of small cells, presumably basal cells (open stars), residing next to the basement membrane. The lumen (solid stars) is reduced to a sliver and contains an amorphous material. Principal cells are dramatically reduced in size compared to those of normal fertile patients, and no microvilli or apical blebs are evident on their apical surface. While these cells contain numerous ribosomes, they present a paucity of endoplasmic reticulum (ER) cisternae and lysosomes and a nondescript Golgi apparatus, features characteristic of undifferentiated cells. F indicates fibrocytes; N, nuclei of principal cells. (a) 200x; (b) 200x; inset, 280x; (c) 7800x.