Comparative testis structure and function in three representative mice strains.

Area of Science:

• Reproductive Biology
• Experimental Models
• Mouse Strains

Background:

• Mice are crucial experimental models, particularly for molecular biology and transgenesis.
• Despite their widespread use, detailed reproductive biology data across different mouse strains remain limited.
• Understanding strain-specific reproductive variations is essential for accurate research outcomes.

Purpose of the Study:

• To comparatively analyze testis structure and function in mature male mice of commonly used inbred (C57BL/6, BALB/c) and outbred (Swiss) strains.
• To identify significant differences and similarities in key reproductive parameters among these strains.
• To investigate the Leydig cell (LC) to macrophage ratio within the testicular environment.

Main Methods:

• Comparative evaluation of testis structure and function parameters.
• Analysis of sperm production, spermatogenesis duration, Sertoli cell number, and spermatogenic efficiency.
• Assessment of Leydig cell proportion, anogenital index, estradiol and testosterone levels, and 3β-HSD expression.
• Quantification of the ratio between Leydig cells and macrophages in the testicular interstitium.

Main Results:

• Swiss mice exhibited significant variations, including higher sperm production compared to C57BL/6 mice.
• Spermatogenesis duration, Sertoli cell number, and spermatogenic efficiency were consistent across strains.
• Swiss mice had higher Leydig cell (LC) proportions but a smaller anogenital index.
• Estradiol levels were lower in C57BL/6 mice; testosterone levels and 3β-HSD expression were similar.
• A high ratio of approximately 1.6 macrophages per Leydig cell was observed in BALB/c mice.

Conclusions:

• Significant variations exist in testicular parameters among commonly used mouse strains, impacting research reproducibility.
• Key aspects of spermatogenesis are conserved, but strain differences in sperm production and Leydig cell populations are notable.
• The high proportion of macrophages relative to Leydig cells warrants further investigation for its implications on testicular function and spermatogonial biology.