Initial segment of the epididymis on days 10 and 59 post treatment. A. Control section on day 10 showing the narrow cell (NC), whose apical cytoplasm protrudes (arrow) into the lumen. Principal cell (PC) nuclei lie beneath the narrow cell. B. ICI 182,780 treated section on day 10 showing two narrow cells with more extensive apical cytoplasmic vesiculation extending into the lumen (arrows). C. Control day 59 showing normal epithelium with narrow cells having a modest extension into the lumen (arrow). D. ICI-treated day 59 showing a narrow cell extension (arrow) into the lumen, similar to that seen on day 10. Bars = 12.5 μm.