FIGURE 4.

Immunofluorescence labeling of CCs from the cauda epididymis

Immunofluorescence labeling of CCs from the cauda epididymis after in vivo luminal perfusion with a control solution adjusted to the resting pH of 6.6 (A) or with an activating solution containing bicarbonate and the cAMP permeant analog cpt-cAMP (B). Horseradish peroxidase (HRP) was added to both solutions to label endosomes (red). Epididymis sections were labeled for the V-ATPase B1 subunit (green). Arrows indicate the frontier between the apical cytoplasm and the base of microvilli. Short microvilli labeled for the V-ATPase are detected in the resting CC shown in A. The yellow color in A shows colocalization of V-ATPase in HRP-containing endosomes located in the subapical pole of clear cells. In the activated CC shown in B, the V-ATPase is mainly located in longer and more numerous microvilli (green), and it is absent from the apical endosomes that contain the internalized HRP (red). Scale bars = 5 μm. Figure reproduced from Ref. 125 with permission from the American Society of Andrology.