Testicular function in cultured postnatal mouse testis fragments is similar to that of animals during the first wave of spermatogenesis.

Background Previously, we evaluated optimal organ culture conditions to produce elongated spermatids in an in vitro mouse testis culture system. However, differences in testicular function between the cultured testis fragments and animal testis have not been determined. Methods To examine how closely cultured testis fragments in vitro approximates what typically occurs during the first wave of spermatogenesis in vivo, C57BL/6J mouse testis fragments obtained on postnatal day (PND) 5 were cultured in AlbuMAX (TM) I/ alpha-Minimal Essential Medium for 15, 23, 30, 35, 42, and 49 days, and compared to mouse testes obtained at PND 5, 14, 20, 24, 28, 30, 35, and 40. At the specified days of culture or PND of mice, the following analyses were conducted: histology, flow cytometry for haploid cell detection, qPCR for spermatid markers, and liquid chromatography/mass spectrometry for testosterone levels. Results Round spermatids were initially observed at 23 days, and their percentage of the total number of cells continued to increase with culture time, as did gene expression of the spermatid markers and haploid cell percentage in the cultured testis fragments. These results were similar in temporal sequence to those in animals. Testosterone levels in the testis fragments reached a maximum at Day 49. Conclusion These findings show this in vitro mouse testis organ culture model may be a useful and convenient tool for mechanistic studies. However, because germ cell differentiation in all seminiferous tubules was not observed, improvements in the system/methods are needed to more closely replicate spermatogenesis as observed in animals.