Follicular dynamics in neonate vitrified ovarian grafts after host treatment with melatonin

Abstract

This study evaluates the effect of melatonin on follicular dynamics in neonate
vitrified ovarian grafts. Vitrified ovaries from neonate F1 hybrid mice, candidates
for transplantation to treated or non-treated groups, were thawed under
standard conditions with or without the addition of 100 μM melatonin, respectively.
Following transplantation, melatonin (20 mg/kg/day) or saline solution
was injected i.p. into the treated and the non-treated groups, respectively.
Vaginal cytology to monitor estrogenic activity together with follicle survival
and development in the ovary grafts was examined.

The results showed that the sites of transplantation became obvious within the
oestrous phase. Histological analysis showed that there was a dynamic of the
ovogenesis process in the vitrified ovary grafts. However, in the ovary graft the
empty cavity together with jumbled oocyte-granulosa complex in the non-treated
group was higher than in the melatonin treated group.

Overall, the number of primary follicles in the ovary grafts of both groups remained
constant throughout the oestrous period. However, the treated ovary
grafts contained more secondary follicles throughout the oestrous period in
comparison to non-treated ovary grafts. The antral follicle rates were more
marked in the melatonin treated group than in the non-treated group during
the oestrous period, whereas at other days of the cycle no significant difference
was observed. The fresh corpora lutea rates were significantly higher in
the treatment group than in the non-treatment group.

The study showed that there is a positive effect with melatonin resulting in
more grafts restoring puberty. Furthermore, the associated increase in healthy
follicles suggests that melatonin has a preventative ischaemia/antioxidant action
and may be useful to follicles. (Folia Morphol 2011; 70, 1: 18-23)