Morphometry and residual strain in porcine ureter

Area of Science:

• Biomedical Engineering
• Physiology
• Urology

Background:

• Recent research indicates that organs like blood vessels and the trachea are open sectors in their zero-stress state, not closed rings.
• Accurate stress and strain analysis necessitates understanding the organ's intrinsic zero-stress configuration.

Purpose of the Study:

• To investigate the morphometry of the porcine ureter in its zero-stress and no-load states.
• To quantify residual strains and opening angles in the ureter.
• To establish correlations between ureteral morphometry, residual strain, and opening angles.

Main Methods:

• The study involved dissecting porcine ureters into rings and then into sectors to characterize the zero-stress state.
• Measurements included outer and inner circumferences, cross-sectional wall area, and the number of buckles.
• Opening angles were measured, and residual strains were analyzed in the circumferential direction.

Main Results:

• Significant axial variation was observed in ureteral morphometry, with peak values proximally.
• Residual strain in the circumferential direction was significant but exhibited no axial variation.
• Opening angles varied along the ureter, ranging from approximately 30 degrees at the ends to 90 degrees in the mid-section.

Conclusions:

• The porcine ureter's zero-stress state is characterized by open sectors with significant residual strains.
• Opening angles correlate with wall thickness, outer circumference residual strain, and outer circumference length.
• Accounting for residual strains is essential for accurate physiological studies of ureteral function, particularly urine transport.