Objective To observe the expression of aquaporin-7 (AQP-7)during the development of renal tubules of mice,and investigate the relationships between AQP-7 and renal tubule development.Methods Kidneys were selected from mice at embryonic days(E)12,14,17,and 18 and postnatal days(P)1,3,7,14,24,40 and 70.The expression of AQP-7 was observed by immunohistochemical(IHC)method in renal tubules.The surface area density values of AQP-7 positive expression were measured by stereological method while the content variation of AQP-7 in the renal tissue of mice was examined by Western blot.Results IHC analysis showed that AQP-7 was expressed in developing renal tubules at the proximal tubule at E14 day,localized along the brush border of the proximal straight tubules (S3 segment)where the cortex and outer medullalie after P14 d,but AQP-7 was not observed in the nephrogenic zone or inner medulla.The results of stereology discovered that the surface area density values of AQR-7 had increased gradually in the apical of renal tubule and reached the maximum at P24 d and then remained stable with the growth of mice.Western blot indicated that AQP-7 expression in kidneys had reached the peak at P24 d and remained stable.Conclusion The expressions of AQP-7 in the developing renal tubules of mice show a chronological and spatial sequence,which plays an important role in water and glycerol balance of mouse kidneys at the late stage of development.

BACKGROUND:The temporal and spatial expression of fibroblast growth factor receptors 1 and 2 remains a controversial issue during kidney development,so the relationship between them and kidney development remains unclear. OBJECTIVE:To observe the dynamic expression of fibroblast growth factor receptors 1 and 2 during kidney development of mice,and to investigate the relationship between them and kidney development. METHODS:The kidneys of fetal mice[embryotic days(E)12,14,16,and 18]and neonatal mice[neonatal days(N)1,3,7,14,24,and 40]were selected to examine the temporal and spatial expression of fibroblast growth factor receptors 1 and 2 by immunohistochemistry method in kidney tissues,and quantitative analysis was performed using western blot assay. RESULTS AND CONCLUSION:(1)Immunohistochemistry showed that fibroblast growth factor receptor 1 was mainly localized in metanephric tissue surrounding the tip of the ureteral bud at E12.Subsequently,fibroblast growth factor receptor 1 was expressed in immature renal corpuscles at various stages,some distal convoluted tubules and capillary loops.The positive site was mainly concentrated in the generative region.Fibroblast growth factor receptor 2 was initially expressed in both ureteral buds and metanephric tissue.Fibroblast growth factor receptor 2 was localized in immature renal corpuscles,distal tubules,collecting ducts and thin segments of medullary loops with kidney development.However,the expression of renal corpuscles was weak.(2)Stereology and western blot assay showed that the expression of fibroblast growth factor receptor 1 was high before birth and gradually decreased after birth,while the expression was very low after N7 day.The expression level of fibroblast growth factor receptor 2 increased gradually with the kidney development and tended to be stable after N7 day.(3)The results exhibit that fibroblast growth factor receptors 1 and 2 are expressed spatially and temporally during kidney development.It is speculated that fibroblast growth factor receptors 1 and 2 may influence nephron development and maturation,and fibroblast growth factor receptor 2 is critical during the formation of ureteral buds and morphology.