精巣の硬さを指標とした精子形成能の新規定量的評価

―精子形成不全ハムスターを用いて―

抄録

Background and Aims : Non-obstructive azoospermia (NOA) is one of the most serious causes of male infertility. Microdissection testicular sperm extraction (MD-TESE) is a first-line therapy of NOA ; however, sperm retrieval rate from MD-TESE differs substantially between surgeons and is generally insufficient. To develop a new accessible method to identify seminiferous tubules with sperm in real time during MD-TESE, we have made a hypothesis that the hardness of seminiferous tubule wall is available as a quantitative index for the presence of sperm. In this study, as a first step, we determined the stiffness of the testis from an animal model of NOA using a measuring system that we designed.

Methods : Male Syrian hamster with bilateral experimental cryptorchidism was used as a NOA model. Stiffness of the testis was evaluated with two different indices of stiffness value : K_j (the stiffness value in a small interval) and K (the mean of K_j values) by using an indentation instrument with a micro force sensor.

Results : Hamster testis was confirmed to be valid as a dynamic model for physical measurements by checking the dependency of stiffness and viscosity on the reaction force generated in indentation procedure. Both stiffness values of the testis with cryptorchidism were significantly decreased compared with those of the control testis.

Conclusion : The results suggest that our system is useful for quantitative evaluation of testis stiffness. Testis hardness has promise for a new index for spermatogenesis. As the next step, we need this approach to permit measurement for seminiferous tubules.