Reproduction Abstracts

Germ stem cells in the testis reside in a unique microenvironment, known as the ‘niche’. In humans testicular germ cell cancer (TGCC) is thought to arise when the ‘niche’ fails to induce germ cell maturation. Gonocytes that fail to differentiate into spermatogonia during fetal life form pre-neoplastic carcinoma in-situ (CIS) cells. CIS cells then transform into an invasive tumour in adulthood. Despite the lack of an animal model of TGCC it may be possible to mimic the ‘niche’ by developing a testicular re-aggregation system. Such a system could be used to recapitulate ‘niche’ conditions which prevent gonocyte maturation. E17.5 Wistar rat testes were dissociated and grafted into castrate nude mice. After 2 weeks, grafts were retrieved and immunohistochemistry for markers of germ, Sertoli, Leydig, and peritubular myoid (PTM) cells was performed. Subsequent experiments used this approach to introduce GFP gonocytes from e15.5 rats into re-aggregated seminiferous cords of e19.5 rat testes. Morphological analysis of retrieved tissue showed seminiferous cord reformation with Sertoli, germ, and interstitial cells readily identifiable histologically. The cords were surrounded by a PTM cells which expressed SMA. AMH expression was not observed in SOX9+ cells suggesting Sertoli cell immaturity. Leydig cells were primarily in the interstitium although some intratubular 3βHSD positive cells were identified. E15.5 GFP gonocytes into e19.5 rat seminiferous cord mixing experiments are underway and will be presented. Testis dissociation and re-aggregation represents a useful model to investigate seminiferous cord formation and its disruption which may be useful for investigating the origins of TGCC.