Histological evaluation of the male rabbit urethra: Regional and age-related variations and their relevance in tissue engineering and reconstructive surgery applications

Abstract

Background data: The male rabbit is the most frequently utilized animal model for urethral preclinical experiments. Surprisingly, little is known about the regional variations in the tissue along the urethra, or how age influences these differences. Objective: To examine the histological changes during healthy ageing in the different regions of the rabbit urethra. Methods: Healthy New Zealand White rabbits of 3, 8 and 21 weeks of age were selected for the study. The rabbits’ urethrae were analyzed by histochemical and immunohistochemical methods, with focus on the smooth and skeletal muscle layers, and the extracellular matrix (ECM) components. Results: The rabbits' urethrae displayed significant similarities to human male urethra. The proximal and middle third of the urethrae were histologically characterized by an abundance of smooth muscle, while the distal third was composed of numerous sinusoids scattered among smooth muscle bundles that are decreasing in thickness and uniformity with increasing age. Age-related histological changes occurred in the urethra at a significant rate. Conclusion: Our results demonstrate that the male rabbit urethra displays significant regional differences, which are influenced by age. It is therefore crucial to select an appropriate age range when designing preclinical studies for the evaluation of urethral reconstruction approaches.