Related Experiment Video
Updated: Jan 29, 2026

Enrichment of Pachytene Spermatocytes and Spermatids from Mouse Testes Using Standard Laboratory Equipment
Published on: September 17, 2019
Reverse transcriptase inhibitors enable the generation of fertile spermatids from fetal mouse testes in vitro
Mayuka Nishida1, Yukina Ono-Sunagare1, Sayuri Kato1
1Laboratory of Biopharmaceutical and Regenerative Sciences, Institute of Molecular Medicine and Life Science, Yokohama City University Association of Medical Science, Yokohama, Kanagawa, Japan.
None:
Organ culture systems enabling in vitro spermatogenesis from neonatal mouse testes exist, but differentiation from fetal testes shortly after sex determination remains unsuccessful. Here, we report the in vitro generation of fertile haploid cells from E12.5 fetal testes. While optimizing in vitro spermatogenesis protocols for neonatal testes, we find that supplementing the culture medium with reverse transcriptase inhibitors (RTIs) significantly improves the efficiency of spermatogenesis, by suppressing retrotransposon activity and protecting genomic integrity. Applying this approach, we successfully induce spermatogenesis through to the elongating spermatid by culturing E12.5 fetal testes under hypoxic conditions in RTI-supplemented medium. Notably, microinsemination using in vitro-derived spermatids produces healthy and fertile offspring, confirming their functional competence. These findings demonstrate the faithful in vitro recapitulation of testicular development and complete spermatogenesis from an early fetal stage, providing a valuable platform for investigating early germ cell development and reproductive biology.
Related Concept Videos
In Vitro Fertilization
The IVF process begins with ovarian stimulation, during which reproductive endocrinologists prescribe hormonal medications to stimulate the ovaries to produce multiple eggs instead of the single...
Fertilization
Eukaryotic Transcription Inhibitors
Eukaryotic transcription inhibitors usually contain two distinct domains, a...
Fetal Circulation
Two umbilical arteries transport blood from the fetus to the placenta. At the placenta, the blood absorbs oxygen and nutrients while simultaneously eliminating waste products. This oxygen-enriched and nutrient-rich blood then returns to the fetus through one...
In Vitro Drug Dissolution: Compendial Testing Models I
In Vitro Drug Dissolution: Compendial Testing Models II

