Abstract This study aimed to investigate the effect of growth and differentiation factor 9 (GDF-9) during the in vitro culture of isolated caprine early antral follicles. The isolated and selected early antral follicles were individually cultured for 18 days, and the following treatments were tested: α-MEM+ (control treatment) or α-MEM+ supplemented with 200 ng/mL GDF-9. The following endpoints were evaluated: follicular growth and morphology, estradiol production, oocyte nuclear maturation, and relative expression of key genes related to steroidogenesis (CYP19A1, CYP17, and insulin receptor) and basement membrane remodeling (MMP-9 and TIMP-2). In both treatments, a decrease was observed in the percentage of morphologically intact follicles with a concomitant increase in the rates of extruded and degenerated follicles (P < 0.05). The GDF-9 treatment showed higher rates of extruded follicles only on day 6 of culture (P < 0.05). Follicle diameter increased progressively throughout the culture period (P < 0.05) with similar diameters between treatments at all culture times (P > 0.05). Growth and differentiation factor 9 increased the daily growth rate from the first to the second third of culture, with higher values (P < 0.05) than control in the second third. Oocyte maturation rate as well as estradiol levels and relative mRNA expression for CYP19A1, CYP17, MMP-9, TIMP-2, and insulin receptor genes were similar between treatments (P > 0.05). This study shows for the first time that GDF-9 added to a culture medium increased the follicle growth rate of goat early antral follicles cultured in vitro.

Resumo Este estudo teve como objetivo investigar o efeito do GDF-9 durante o cultivo in vitro de folículos antrais iniciais caprinos isolados. Os folículos antrais iniciais isolados e selecionados foram cultivados individualmente por 18 dias, e os seguintes tratamentos foram testados: α MEM+ (tratamento controle) ou α-MEM+ suplementado com 200 ng/mL de GDF-9 (tratamento GDF-9). Os seguintes parâmetros foram avaliados: crescimento e morfologia folicular, produção de estradiol, maturação nuclear do oócito e expressão relativa de genes-chave relacionados a esteroidogênese (CYP19A1, CYP17 e receptor de insulina) e remodelamento da membrana basal (MMP-9 e TIMP-2). Em ambos os tratamentos, observou-se diminuição na porcentagem de folículos morfologicamente intactos com aumento concomitante nas taxas de folículos extrusos e degenerados (P < 0,05). O tratamento GDF-9 apresentou maiores taxas de folículos extrusos apenas no 6º dia de cultivo (P < 0,05). O diâmetro do folículo aumentou progressivamente ao longo do período de cultivo (P < 0,05) com diâmetros semelhantes entre os tratamentos em todos os tempos de cultivo (P > 0,05). O GDF-9 aumentou a taxa de crescimento diário do primeiro para o segundo terço de cultivo, sendo maior (P < 0,05) que o controle no segundo terço. A taxa de maturação oocitária assim como os níveis de estradiol e a expressão relativa de RNAm para os genes CYP19A1, CYP17, MMP-9, TIMP-2 e receptor de insulina foram similares entre os tratamentos (P > 0,05). Em conclusão, este estudo mostra pela primeira vez que GDF-9 adicionado a um meio de cultivo aumentou a taxa de crescimento de folículos antrais iniciais caprinos cultivados in vitro.

Abstract Due to the great interest in ovarian cryopreservation and, consequently conservation and restoration of female fertility in the last decades, different vitrification procedures (vitrification devices or solutions) have been developed, patented, and used both for academic research purposes and for clinical use. Therefore, the present study aimed to provide a systematic review and meta-analysis of data obtained from the application of different patented and non-patented vitrification devices and solutions in different countries. For this purpose, relevant observational studies published between the years 2000 to 2021 were selected to verify the efficiency of ovarian vitrification processes on parameters such as morphology, viability, and apoptosis in preantral ovarian follicles after transplantation or in vitro culture. Our research revealed that, although several countries were considered in the study, the United States and Japan were the countries that registered the most processes, and 22 and 16 vitrification devices and solutions out of a total of 51, respectively were patented. Sixty-two non-patented processes were also considered in the study in all countries. We also observed that transplantation and in vitro ovarian culture were the techniques predominantly used to evaluate the efficiency of the devices and vitrification solutions, respectively. In conclusion, this review showed that patented or non-patented protocols available in the literature are able to successfully preserve preantral follicles present in ovarian tissue. Despite the satisfactory results reported so far, adjustments in ovarian vitrification protocols in order to minimize cryoinjuries to the follicles remain one of the goals of cryopreservation and preservation of the female reproductive function. We found that vitrification alters the morphology and viability, and offers risks leading in some cases to follicular apoptosis. However, adjustments to current protocols to develop an optimal procedure can minimize damage by not compromising follicular development after vitrification/warming.