Pathogenesis of extra efferent vessel development in diabetic glomeruli

Area of Science:

• Nephrology
• Diabetic Nephropathy
• Renal Anatomy

Background:

• Diabetic glomerulopathy involves unique vascular changes, including extra efferent vessels (EEVs).
• Previous studies indicated up to 5 EEVs per glomerulus, potentially acting as shunts.
• The correlation between EEVs and diabetic lesion severity was previously unquantified.

Purpose of the Study:

• To confirm and extend previous findings on the prevalence and structure of EEVs in diabetic glomerulopathy.
• To investigate the relationship between EEVs and the severity of diabetic glomerular lesions.
• To elucidate the potential functional role of EEVs in diabetic nephropathy.

Main Methods:

• Analysis of 18 diabetic kidney cases with varying lesion severity and 10 controls.
• Three-dimensional reconstruction of glomeruli using complete photographic methods.
• Microscopic examination of EEV structure and connection to glomerular vasculature.

Main Results:

• Diabetic cases exhibited up to 18 EEVs per glomerulus, significantly more than controls.
• EEVs possess muscular walls, resembling efferent arterioles, and exit glomeruli via existing gaps.
• The highest number of EEVs were observed in long-standing Type 2 Diabetes Mellitus cases with mild to moderate lesions.
• Numerous anastomoses were found among efferent glomerular capillaries in both normal and diabetic glomeruli.

Conclusions:

• EEVs are common and numerous in diabetic glomeruli, suggesting a role in preserving glomerular function.
• EEV formation represents a significant, hemodynamically induced glomerular remodeling in diabetes.
• EEVs likely do not act as shunts or restrict local glomerular outflow.
• EEV development may be linked to increased glomerular inflow, possibly due to afferent arteriole damage.