Figure 3.

Assessment of tear production and sweat secretion. (A) Tear production as assessed by Schirmer's test in the patient and in 4 control subjects. Results demonstrate bilateral hypolacrimia in the patient. Median and IQR. (B) Exemplary images from starch-iodine test in the patient. The starch-iodine reaction does only occur in the presence of water, indicated by dark discoloration. Axillae are more severely affected from hypohidrosis than palmar aspects of hands. (C) Quantitative assessment of sweat secretion before and after exercise in the patient and in 5 control subjects, indicating reduced basal and stimulated sweat secretion rates in both patient axillae. Median and IQR. (D,E) Immunohistochemical staining of claudin-10 in axillary skin biopsy specimens. In patient and control samples, claudin-10 (pink) is well-detectable and localizes to secretory tubules of eccrine sweat glands but is not found in excretory ducts (nuclei in dark blue). (D) Scale bars, 50 μm (left column) or 20 μm (right column). (E) demonstrates the loss of claudin-10 expression as a secretory tubule merges into an excretory duct (arrow) in a control specimen. Scale bar, 20 μm. (F) Immunofluorescence labeling of secretory tubules from eccrine sweat glands. In both patient and control samples, claudin-10 predominantly localizes to canaliculi (arrows), whereas occludin localizes to membranes lining the lumen and is found in canaliculi to a lesser extent. Nuclei are stained with DAPI (blue). Scale bars, 10 μm.