in 2001, an anomaly of the kidneys was found. The lower ends of the kidneys were fused by a renal substance and formed a horseshoe kidney located ventral to the abdominal aorta and inferior vena cava. Both renal hila opened very widely in the ventral direction, with the left hilum being larger than the right. This horseshoe kidney had original left and right renal arteries that branched from the abdominal aorta. As well, there were four surplus renal arteries. The first surplus artery branched from the right renal artery and was distributed to the upper pole of the right kidney. The second arose from the abdominal aorta and was distributed to the inferior pole of the right kidney. The third arose from the abdominal aorta and was distributed to the inferior pole of the left kidney and part of the isthmus. The fourth branched from the abdominal aorta and was distributed to the upper pole of the left kidney. The incidence of horseshoe kidneys in Japanese anatomical dissections has been reported as 0.15-0.48%. This was the sixth such case for our laboratory, representing a frequency of 0.1% (6 of 1902 dissections) from 1952 to 2001.

Summary: Sjögren's syndrome (SS) is an autoimmune disorder whose main symptoms include xerostomia and dry eyes. It has been demonstrated that abnormal expression of aquaporin (AQP)-5 in the parotid and submandibular glands in SS model mice was corrected by cevimeline. In the present study, we orally administered cevimeline hydrochloride (cevimeline) to female MRL/l mice, which are widely used as a model for SS, to immunohistochemically investigate the localization of AQP-5 in the salivary glands. We also assessed the ultrastructure of acinar cells in the submandibular glands. AQP-5 was expressed in the apical and lateral cell membranes of acinar cells in the parotid and submandibular glands of normal mice, but not in the sublingual glands. In contrast, AQP-5 was expressed not only in the cell membranes in the apical domains but also in the cytoplasm in the SS model mice, indicating that the localization of AQP-5 was disordered in the SS model mice. After administration of cevimeline, AQP-5 was predominantly localized in the cellular apical domains of the acinar cells. Electron microscopy revealed that administration of cevimeline to the SS model mice and normal mice markedly reduced the number of secretory granules, increased the area of the rough endoplasmic reticulum, and expanded the intercellular gaps in the cells of the submandibular acini. Condensed vacuoles were also observed in the Golgi apparatuses, indicating that secondary enhancement of secretion and production of saliva had occurred. Consequently, the results of the present study demonstrate that the administration of cevimeline to the SS model mice increased salivary secretion in the submandibular glands. Furthermore, cevimeline transiently normalized the localization of AQP-5 expression in the parotid and submandibular glands.

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