Figure 13. Release of obstruction prevents HoxB7-derived collecting duct loss:

(A) Kidneys from HoxB7Cre;mTmG mice showed GFP expression in all the collecting ducts. Obstructed kidneys at 1 week displayed flattening of collecting duct cells in the more preserved kidney areas (yellow arrows). Continued obstruction leads to a significant loss in tubular epithelium at 3 weeks (white arrows), which was restored to normal state at 2W post-release. Scale bars, 50μm. (B) Scatter plot shows cumulative mean ± SE of percent GFP⁺ collecting duct area fraction of left kidneys subjected to various surgical procedures. A significant loss in collecting duct area is seen in 3 weeks obstructed kidneys (n=3) in comparison to sham-operated mice (n=3), with a progression in the damage between one week (n=3) to 3 weeks. Two of the animals in 3W age group with higher hydronephrosis index (3) displayed a complete loss of tubular epithelium in comparison to the obstructed kidneys with moderate hydronephrosis index (2). The collecting duct area in released kidneys at 2 weeks post-release (n=3) was not significantly different from sham-operated kidneys but significantly different compared to the 3W obstructed group (*P<0.05; NS-Non significant). (C) qRT-PCR analysis for Hoxb7 gene expression in 3 week age group of sham-operated (n=4), obstructed (n=6) and released (n=5) animals revealed no significant changes in kidneys due to surgical treatments (NS-Non significant).