The aim of this narrative review is to provide an overview of the currently used experimental injection techniques for SSC transplantation in animal and human testes. This is crucial in understanding and determining the role of the different techniques necessary for successful transplantation.
A comprehensive review of peer-reviewed publications on this topic was performed using the PubMed and Google Scholar databases. The search was limited to English language work and studies between 1994 (from the first study on SSC transplantation) and April 2019. Key search terms included mouse, rat, boar, ram, dog, sheep, goat, cattle, monkey, human, cadaver, testes, SSC transplantation, injection and technique.
This review provides an extensive clinical overview of the current research in the field of human SSC transplantation. Rete testis injection with ultrasonography guidance currently seems the most promising injection technique thus far; however, the ability to draw clear conclusions is limited due to long ischemia time of cadaver testis, the relatively decreased volume of the testis, the diminishing size of seminiferous tubules, a lack of intratesticular pressure and leakage into the interstitium during the injection on human cadaver testis. Current evidence does not support improved outcomes from multiple infusions through the rete testes. Overall, further optimization is required to increase the efficiency and safety of the infusion method.
Identifying a favourable injection method for SSC transplantation will provide insight into the mechanisms of successful assisted human reproduction. Future research could focus on reducing leakage and establishing the optimal infusion cell concentrations and pressure.
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