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.

O presente trabalho investigou a taxa de degeneração de folículos primordiais caprinos in situ após conservação em PBS ou TCM 199, em diferentes temperaturas e tempos de incubação. Para cada animal, o par ovariano foi dividido em 19 fragmentos. Um fragmento foi escolhido aleatoriamente e imediatamente fixado (controle). Os 18 fragmentos ovarianos restantes foram aleatoriamente distribuídos em tubos contendo PBS ou TCM 199 e conservados a 4, 20 or 39ºC por 4, 12 or 24h. A conservação de fragmentos ovarianos em PBS ou TCM 199 a 20ºC por 12 e 24h ou a 39ºC, em todos os tempos de incubação testados, aumentou significativamente a percentagem de folículos primordiais degenerados (P<0,05). Ao contrário, em ambos os meios testados, a taxa de degeneração de folículos primordiais conservados a 4ºC em todos os tempos testados e a 20ºC por 4h foi similar ao controle (P>0,05). Em conclusão, este estudo mostrou que o PBS foi tão eficiente quanto o TCM 199 na conservação de folículos primordiais caprinos in situ, sendo os melhores resultados observados na temperatura de 4ºC.

The present work has investigated the degeneration rate of goat primordial follicles in situ after preservation in PBS or TCM 199 at different temperatures and incubation times. For each animal the ovarian pair was divided into 19 fragments. One ovarian fragment was taken randomly and immediately fixed (control). The other 18 ovarian fragments were randomly distributed in tubes containing PBS or TCM 199 and stored at 4º, 20º or 39ºC for 4, 12 or 24h. The storage of ovarian fragments in PBS or TCM 199 at 20ºC for 12h and 24h or at 39ºC, in all incubation times tested, increased significantly the percentage of degenerated primordial follicles (P<0.05). In contrast, for both media tested the degeneration rate of primordial follicles preserved at 4ºC for up to 24h and at 20ºC for 4h was similar to control values (P>0.05). In conclusion, this study shows that PBS was as efficient as TCM 199 in the preservation of goat primordial follicles in situ, being the best results observed at 4ºC.

O presente estudo investigou a eficiência da solução salina e solução à base de água de coco na preservação de folículos pré-antrais inclusos em tecido ovariano, em diferentes temperaturas e diferentes tempos de incubação. No abatedouro, o par ovariano foi dividido em 19 fragmentos; um fragmento ovariano foi imediatamente fixado para histologia clássica (controle-tempo zero). Os outros 18 fragmentos ovarianos foram conservados em ambas as soluções a 4ºC, 20ºC ou 39ºC por 4 h, 12 h ou 24 h. A análise histológica mostrou que a conservação de fragmentos ovarianos em ambas as soluções a 4ºC por até 24 h mantém a percentagem de folículos pré-antrais normais similar aos valores do controle. Ao contrário, a conservação a 20°C ou 39ºC, em ambas as soluções, reduziu significativamente a percentagem de folículos pré-antrais normais comparado aos valores do controle, exceto em solução salina a 20ºC por 4 h ou em solução à base de água de coco a 20ºC por 4 h e 12 h. Em conclusão, esse estudo mostrou que ambas as soluções podem ser usadas com igual eficiência para conservar folículos pré-antrais caprinos a 4°C, independente do tempo de incubação. No entanto, para conservar folículos pré-antrais caprinos a altas temperaturas, a solução à base de água de coco é recomendada.

The present study investigated the efficiency of saline solution and coconut water solution in the preservation of goat preantral follicles enclosed in ovarian tissue, at different temperatures and for different incubation periods. At the slaughterhouse, the ovarian pair was divided into 19 fragments; one ovarian fragment was immediately fixed for histology (control-time zero). The other 18 ovarian fragments were preserved in both solutions at 4ºC, 20ºC or 39ºC for 4 h, 12 h or 24 h. The histological analysis showed that the storage of ovarian fragments in both solutions at 4ºC for up to 24 h kept the percentage of normal preantral follicles similar to the control values. In contrast, preservation at 20°C or 39ºC, in either solution, reduced significantly the percentage of normal preantral follicles compared to the control values, except in saline solution at 20ºC for 4 h or in coconut water solution at 20ºC for 4 h and 12 h. In conclusion, this study shows that both solutions can be used with the same efficiency to preserve goat preantral follicles at 4°C, irrespective of the incubation time. However, to preserve goat preantral follicles at higher temperatures, coconut water solution is recommended.

O presente trabalho investigou a eficiência da solução salina 0,9% e tampão fosfato salina (PBS) na conservação de folículos pré-antrais caprinos in situ a diferentes temperaturas e tempos de incubação. O par ovariano de cada animal foi dividido em 19 fragmentos. Um fragmento foi escolhido aleatoriamente e fixado (controle). Os outros 18 fragmentos foram distribuídos aleatoriamente em tubos contendo solução salina 0,9% ou PBS a 4, 20 ou 39 °C por 4, 12 ou 24 h. Um total de 5.921 folículos pré-antrais foram analisados. A qualidade dos folículos pré-antrais foi avaliada através de histologia clássica. A incubação de fragmentos ovarianos em solução salina 0,9% ou PBS a 4 ºC não reduziu significativamente a percentagem de folículos morfologicamente normais quando comparados com o controle, exceto após a conservação em solução salina 0,9% por 24 h. A incubação de fragmentos ovarianos a 20 ou 39°C reduziu a percentagem de folículos pré-antrais normais quando comparados com o controle, exceto após conservação em PBS a 20°C por 4 h. Em conclusão, este estudo mostrou pela primeira vez que folículos pré-antrais caprinos podem ser conservados in situ com sucesso a 4 ºC em solução salina 0,9% por 12 h e em PBS por 24 h, e a 20 ºC em PBS por 4 h.

The present work investigated the efficiency of 0.9% saline solution and Phosphate Buffered Saline (PBS) in the preservation of goat preantral follicles in situ at different temperatures and incubation times. The ovarian pair of each animal was divided into 19 fragments. One ovarian fragment was taken randomly and fixed (control). The other 18 fragments were randomly distributed in tubes containing 0.9% saline solution or PBS at 4, 20 or 39 ºC for 4, 12 or 24 h. A total of 5,921 preantral follicles were examined. The quality of preantral follicles was evaluated by classical histology. The storage of ovarian fragments in 0.9% saline solution or PBS at 4 ºC did not reduce significantly the percentage of morphologically normal follicles when compared with the control, except after preservation in 0.9% saline solution for 24 h. The storage of ovarian fragments at 20 or 39°C reduced the percentage of normal preantral follicles when compared to the control, except after preservation in PBS at 20°C for 4 h. In conclusion, this study showed for the first time that goat preantral follicles can be stored in situ successfully at 4 ºC in 0.9% saline solution for 12 h and in PBS for 24 h, and at 20 ºC in PBS for 4 h.