Three-dimensional analysis of partial restoration of spermatogenesis in vitamin A-deficient mice.

Background: An animal model of the partial restoration of spermatogenesis may be useful in the field of reproductive biology and medicine. Vitamin A deficiency (VAD) induces the restorable arrest of spermatogenesis at the level of spermatogonia and is used as a mouse model of spermatogenesis disorder.

Objective: We aimed to establish an animal model in which spermatogenesis is partially restored by switching a vitamin A deficiency diet to a normal vitamin A-containing diet and conduct a comprehensive analysis to identify vulnerable sites in the seminiferous tubules that affect the efficient restoration of spermatogenesis in this model.

Materials And Methods: Mice fed a vitamin A deficiency diet until 12 weeks old and then reared with a normal diet for 15 weeks served as the restoration model. We performed three-dimensional reconstructions of the seminiferous tubules and analyzed the three-dimensional distribution of restored spermatogenesis throughout the testis.

Results: Fifteen weeks after the switch to the normal diet, spermatogenesis was restored in 78% of the length of seminiferous tubules. The percentage of restored spermatogenesis was lower in longer seminiferous tubules. An analysis of the distribution of spermatogenesis throughout the testis in this model revealed that it was restored less in portions of seminiferous tubules near the rete testis and hairpin curves and also in those located in the caudal region of the testis. These sites tended to correspond to sites with fewer spermatogonia in the vitamin A deficiency testis.

Discussion And Conclusions: We established an animal model of the partial restoration of spermatogenesis and examined the three-dimensional distribution of restored spermatogenesis in seminiferous tubules. The results obtained provide insights into the mechanisms underlying spermatogenesis disorders and may contribute to better clinical practices, such as the screening of drugs or therapeutic interventions for human male infertility and improvements in fertility preservation techniques for individuals undergoing chemotherapy.