Does early cell death cause germ cell loss after intratesticular tissue grafting?

Objective: To assess cell death in intratesticular grafts.

Design: Experimental animal study.

Setting: University.

Animal(s): F1-hybrids from SV129 X C57BL.

Intervention(s): Intratesticular tissue transplantation was performed and cell death in the grafts was evaluated at different time points after transplantation.

Main Outcome Measure(s): Apoptotic cell death in spermatogonia was evaluated by flow cytometry with the use of the annexin V assay. Immunohistochemistry was used to evaluate graft development and the global occurrence of cell death.

Result(s): The highest level of spermatogonia-specific cell death was found on days 4 and 10, although no statistical difference was observed compared with control tissue. Statistically significant reductions in tubule integrity were observed 1 day and 2 months after transplantation. More degenerated tubules were observed in the center of the grafts 1 and 4 days after transplantation, and higher numbers of apoptotic tubules were found 1 day after transplantation. No difference in overall cell death was observed between grafts and controls for any time point except for the frozen grafts 1 day after transplantation.

Conclusion(s): Spermatogonia-specific apoptosis does not explain the stem cell loss observed after intratesticular tissue grafting; it probably results from degeneration of tubules in the center of the graft owing to hypoxia during the first days after transplantation.