Endocrine Abstracts

Immature testicular tissue was successfully xenografted in several species but did not lead to spermatogenesis with tissue obtained from the non-human primate Callithrix jacchus. Previous data indicate that the microenvironment provided by the mouse host might cause this failure. We conducted an in vivo study performing autologous ectopic transplantation of testicular fragments in newborn anaesthetised marmoset monkeys and compared transplanted animals to sham operated animals. Our study aimed to prove whether meiosis can be started and whether this technique offers a perspective for fertility preservation in prepubertal (oncological) patients. 18 months after transplantation we found matured transplants in 2 out of 4 grafted animals. Histology and morphometry of the grafts exhibited tubular development up to an intermediate state compared to pre-graft and adult controls. Dividing spermatogonia and primary spermatocytes were present in the tubules of the transplants but arrested at early meiosis. Immunohistochemistry revealed normal maturation of Sertoli cells, Leydig cells and peritubular cells. Chorionic gonadotropin, the hormone controlling Leydig cells of marmosets, increased to castrate levels (sham-operated castrated controls; n=4) in the transplanted animals, while serum testosterone values did not reach to the normal range of intact controls. Meiotic arrest could have occurred in the grafts due to the lack of sufficient testosterone concentrations, or due to hyperthermia caused by the position of the grafts under the back skin. We conclude that autologous grafting in the marmoset is suitable to maintain testicular tissue and allows maturation up to meiosis, even after long-term ectopic storage.