# Morphological Analysis of Intratesticular Structures Affecting Hamster Testicular Stiffness

## TL;DR

This study shows that testicular stiffness in hamsters is linked to changes in testicular structure and spermatogenic activity, suggesting it could be a useful indicator for reproductive health.

## Contribution

The study introduces testicular stiffness as a novel biomechanical indicator of spermatogenic function in animal models.

## Key findings

- Cryptorchid testes showed significantly lower stiffness and structural changes compared to controls.
- Reduced tubule occupancy and diameter, along with increased tunica albuginea thickness, correlate with decreased stiffness.
- Testicular stiffness is strongly related to the Johnsen score, a measure of spermatogenic function.

## Abstract

Animal models of testicular dysfunction provide important insights into mechanisms of impaired spermatogenesis. Herein, a hamster model of experimental cryptorchidism was used to investigate the effect of morphological alterations in testicular structures on overall testicular stiffness by using a stiffness measuring robotic system equipped with a micro-force sensor device. Our results suggest that testicular stiffness is related to spermatogenic activity and may serve as a novel biomechanical indicator in animal-based reproductive research.

Testicular stiffness is a potential indicator of spermatogenic activity. Herein, we investigated the relationship between testicular stiffness and intratesticular morphology in Syrian hamsters by using a robotic system with a micro-force sensor. Animals were divided into control, sham-operated, and surgically induced cryptorchidism groups. Testicular stiffness, testis weight and size, and Johnsen score data for sham and crypt groups were partially derived from our previous study and reanalysed. Testicular stiffness and histological parameters were analysed, including tunica albuginea thickness, seminiferous tubule occupancy, tubule diameter, intratubular cell-layer thickness, peritubular lamina propria thickness, and Leydig cell numbers. Compared with those of sham and normal controls, cryptorchid testes showed significantly lower stiffness and marked morphological changes, such as reduced tubule occupancy and diameter, thinner intratubular cell layers, thickened tunica albuginea and peritubular lamina propria, and increased numbers of Leydig cells. Decreased testicular stiffness and the Johnsen score, a standard index of spermatogenic function, were strongly related to these structural changes. These findings indicate that structural changes in the testes caused by impaired spermatogenesis are related to measurable differences in tissue stiffness. This study supports using mechanical properties as non-invasive quantitative indices to evaluate testicular function in animal models, offering a novel approach for future research in experimental andrology.