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The proximal straight tubular epithelium of the mouse kidney exhibited sexual dimorphism in conventional paraffin sections stained with periodic acid Schiff (PAS) in our preliminary observation. The purpose of this study was to clarify the sex-dependent structural features in the proximal straight tubular cells of the mouse kidney, and to clarify the effects of sex hormones on this portion of the renal tissue.The mice used in this study were divided into intact, orchiectomized, ovariectomized, testosterone-treated and estradiol-treated groups. The kidneys of these animals were examined by histological, cytological and cytochemical (for acid phosphatase reaction) procedures.In the proximal straight tubular epithelium of intact adult mice, PAS staining of the brush border in females was more intense than that in males. Furthermore, PAS-positive granules were observed in the cytoplasm of females only. Orchiectomy changed the male-specific features to that of the females, and treatment with testosterone induced the male-specific features. Ovariectomy and estradiol treatment showed no effects. Ultrastructurally, PAS-positive granules were observed as electron-dense myelinoid bodies, and these contained acid phosphatase-positive matrix.The present study demonstrated apparent sexual dimorphism and effects of testosterone on PAS staining and PAS-positive granules in the proximal straight tubule cells in normal mice. In addition, the association of PAS-positive granules and lysosomes was suggested by cytological and cytochemical examination.

Abstract:We recently demonstrated sexual dimorphism in the S3 segment of the ICR mouse kidney, as differences in periodic acid Schiff (PAS) staining on the brush border and the number and size of PAS-positive granules. However, whether these sex dependent features in the S3 segment of the mouse kidney occur only in the ICR strain or are a general feature also observed in other strains is unclear. In the present study, we examined the renal S3 segment of the ICR, BALB/c, C57BL/6, C3H/He and DBA/2 mice strains, which are commonly used in laboratory experiments. PAS staining of the brush border in females of all strains was more intense than that of males, and PAS-positive granules were detected in all females. In male groups, PAS-positive granules were detected in the DBA/2 strain only, but their number was very few. In addition, PAS-positive giant bodies, larger than the nuclear size, were detected in females except those of the C57BL/6 strain. Histometrical investigation demonstrated apparent strain differences in a number of PAS-positive granules and PAS-positive giant bodies. The ultrastructural and cytochemical investigations suggest that the PAS-positive granules and PAS-positive giant bodies were multilamellar lysosomes. We propose that the present findings are significant for comparative morphology in laboratory animal science. Key words: kidney, mice, PAS, strain, S3 segment well known that the mouse nephron is morphologically different between sexes [6,7,12], and furthermore, we recently reported new sexual dimorphism in the renal S3 segment (proximal straight tubule) of the ICR strain of mice [11]. That study showed the brush border of

ABSTRACT. In the present study, we investigated the sexual dimorphisms, effects of castration and sex hormone treatment, and strain differences in the morphology of mouse kidney by measuring the percentage of renal corpuscles with cuboidal cells in the parietal layer of the glomerular capsule, the diameter of renal corpuscles and the number of nuclei of epithelial cells in the proximal convoluted tubule. In ICR mice, the percentage of renal corpuscles with cuboidal cells and the diameter of renal corpuscles were larger in males than in females, and the numbers of nuclei were lower in males than in females. All of these parameters became similar to those of intact females by orchiectomy, and restored to levels similar to those in intact males after testosterone treatment to orchiectomized males. On the other hand, ovariectomy and estradiol treatment gave no effects to any of these parameters. Similar sexual dimorphisms were observed in BALB/c, C57BL/6, C3H/He and DBA/2 mice as in ICR mice, although the diameter of renal corpuscles was not significantly different between males and females in BALB/c mice. Strain differences were observed in each of these three parameters among the 5 strains. In conclusion, the present study demonstrated sexual dimorphisms, effects of castration and sex hormone treatment, and strain differences in the morphology of mouse kidney by morphometrical analysis.-KEY WORDS: kidney, morphometry, mouse, sex difference, strain difference.

Abstract. The nonobese diabetic mouse is a model of spontaneous insulin-dependent diabetes mellitus. The present study made longitudinal observations of renal lesions in the acute-progressive phase of diabetic mice 0, 10, 20, 30, and 40 days after onset of diabetes without insulin therapy. Plasma creatinine and blood urea nitrogen concentrations gradually increased after onset of diabetes. Kidney weight increased and plateaued at day 20. Under electron microscopy the glomeruli demonstrated only mild changes on day 40. In the proximal tubules proliferating cell nuclear antigen-positive nuclei and nuclear divisions were increased on days 10 and 20. On day 40 of diabetes, increased periodic acid-Schiff-positive granules, confirmed as lysosomal dense bodies, increased neuronal nitric oxide synthase (nNOS) positive reaction, and decreased periodic acid-Schiff staining in the brush border were observed in the proximal straight tubules. In the juxtaglomerular apparatus stratified macula densa were decreased with time in diabetes compared with the findings on day 0, and this macula densa positively reacted with nNOS. No changes in renin levels were observed. In addition, apoptotic cells were not detected. In conclusion, this research represents the first thorough characterization of acute changes in nonobese diabetic mouse kidneys. The results demonstrated renal hypertrophy and slight glomerular injury in early stages and structural alteration of the proximal straight tubules at later stages during the acute phase of diabetes. Furthermore, increased nNOS may represent one of the pathogenic factors of diabetic nephropathy.Key words: Insulin-dependent diabetes mellitus; neuronal nitric oxide synthase; nonobese diabetic mice; renal pathology.The nonobese diabetic (NOD) mouse is an established model of spontaneous insulin-dependent diabetes mellitus (IDDM). 8,20 This strain was derived from the Jcl : ICR cataract mouse at Shionogi Aburai Laboratories, Japan. The incidence of IDDM among NOD mice is dependent on autoimmune pathogenesis and is higher in females than in males. 23,46 The mode of transmission includes a recessive gene in the major histocompatibility complex. 7,12,21 After onset of diabetes, pathologic changes in the NOD mouse resemble those in human IDDM. 34 Diabetic nephropathy (DN) is a major complication of diabetes mellitus and is one of the main causes of death among humans, dogs, and cats. 2,10,24,26,44 In IDDM numerous pathologic investigations of DN have been performed using streptozotocin-treated animals or spontaneous animal models such as the NOD mouse. 9,14,36,37 Complications of various pathogenic factors of DN have been demonstrated using these animal models. Glomerular sclerosis is classically known as a major pathologic change of DN, involving proliferation of mesangial cells, expansion of the mesangium, or thickening of the glomerular basement membrane. 9,14,22,29,33 These glomerular changes frequently develop in the chronic phase of diabetes. The other major change of DN is renal hypertrophy. 15...