To improve the reproductive performance of water buffalo to level can satisfy our
needs, the mechanisms controlling ovarian follicular growth and development should
be thoroughly investigated. Therefore, in this study, the expressions of growth differentiation
factor-9
(GDF-9)
in buffalo ovaries were examined by immunohistochemistry,
and the effects of GDF-9
treatment on follicle progression were investigated using
a buffalo ovary organ culture system. Frozen–thawed buffalo ovarian follicles within
slices of ovarian cortical tissue were cultured for 14 days in the presence or absence
of GDF-9.
After culture, ovarian slices were fixed, sectioned and stained. The follicles
were morphologically analysed and counted. Expression pattern of GDF-9
was
detected in oocytes from primordial follicles onwards, besides, also presented in granulosa
cells. Moreover, GDF-9
was detected in mural granulosa cells and theca cells of
pre-antral
follicles. In antral follicles, cumulus cells and theca cells displayed positive
expression of GDF-9.
In corpora lutea, GDF-9
was expressed in both granulosa and
theca lutein cells. After in vitro culture, there was no difference in the number of primordial
follicles between cultured plus GDF-9
and cultured control that indicated the
GDF-9
treatment has no effect on the primordial to primary follicle transition. GDF-9
treatment caused a significant decrease in the number of primary and secondary follicles
compared with controls accompanied with a significant increase in pre-antral
and
antral follicles. These results suggest that a larger number of primary and secondary
follicles were stimulated to progress to later developmental stages when treated with
GDF-9.
Vitrification/warming of buffalo ovarian tissue had a little remarkable effect, in
contrast to culturing for 14 days, on the expression of GDF-9.
In conclusion, treatment
with GDF-9
was found to promote progression of primary follicle that could provide
an alternative approach to stimulate early follicle development and toimprove therapies
for the most common infertility problem in buffaloes (ovarian inactivity). improve