This study was conducted to assess the effect of melatonin on the structure of
testis and spermatogenesis dynamics in neonate vitrified testis grafts. Neonate
vitrified testes, candidates for transplantation heterotopically to experiment or control
groups, were warmed in thawing media which had or did not have a supplement
of 100 μM melatonin, respectively. Following transplantation, melatonin (20 mg/
/kg/day) or saline solution was intraperitoneally injected into the treated and the
non-treated groups, respectively. The initiating spermatogenesis, spermatogonia
survival, and structure of tissue in the testis graft were examined. Cell apoptosis
(TUNEL assay) and proliferation (Brdu assay) in germ cells were determined.
Histological studies revealed the dynamic of the spermatogenesis process in the
vitrified testis graft. However, dilation of the lumen accompanied by a disorganised
epithelium in the non-treated group was higher than in the treated group. Furthermore,
the proportion of apoptotic germ cells together with a reduced proportion of
proliferated germ cells was higher in the non-treated group than in the treated
group. Overall, the number of seminiferous tubules in the testes grafts of both groups
remained steady. However, the non-treated testes grafts contained more damaged
seminiferous tubules than the treated ones. The thickness of the seminiferous tubules
was greater in the melatonin treated group than in the non-treated group. In
fact, the thickness of germinal epithelium was significantly higher in the treated
group than in the non-treated group. The study may show a positive effect from
melatonin resulting in more grafts restoring puberty. Furthermore, the associated
increase in the healthy number of seminiferous tubules suggests that melatonin may
have a preventative ischaemia/antioxidant role and in fact may be useful to initiate
the spermatogenesis process. (Folia Morphol 2011; 70, 2: 95–102