Figures 18 through 23. The outer layer of the peritubular wall in the caput epididymidis proximal to a congestive obstruction is shown in Figures 18 through 23. Large cells (smooth muscle cells [SMCs]) are interspersed among considerable amounts of collagen (C) and an amorphous substance (asterisks). A continuous and thick basement membrane–like material surrounds the cellular plasma membrane (arrowheads); the cytoplasm is engulfed by thin myofilaments (F) converging to a large number of dense bodies. A developed endoplasmic reticulum winding around the mitochondria is also visible (arrow) as are glycogen granules (gly) scattered among myofilament bundles. The plasma membrane shows an irregular outline because of the presence of crowded micropinocytotic vesicles (V).