Summary: The objective of this study was to evaluate the effects of adding ascorbic acid to the media for in vitro culture of cattle ovarian fragments and to determine their effects on growth activation and viability of early-stage follicles. The ovarian cortex was divided into small fragments; one fragment was immediately fixed (control) and the other fragments were cultured in minimum essential medium (MEM) supplemented or not with various doses of ascorbic acid. Ovarian tissue was processed for histology, transmission electron microscopy (TEM) and immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA). Compared with control fragments, the percentage of primordial follicles was reduced (p < 0.05) and the percentage of growing follicles had increased (p < 0.05) in cultured cortical fragments, independent of the tested medium or incubation time. Furthermore, compared with control tissue, culture of ovarian cortex for 8 days reduced the percentages of healthy, viable follicles (p < 0.05), but not when cultures were supplemented with 25, 50 or 100 μg/ml of ascorbic acid. Ultrastructural and immunohistochemical analysis of 8 day cultured ovarian cortical fragments, however, showed the integrity and viability of follicles only when fragments were cultured in presence of 50 μg/ml of ascorbic acid. In conclusion, this study demonstrated that addition of ascorbic acid to MEM at a concentration of 50 μg/ml not only stimulates the activation of 8 day in vitro cultured cattle primordial follicles and subsequent growth of activated follicles, but also safeguards the viability of these early-stage follicles.

RESUMO Objetivou-se avaliar o consumo, a digestibilidade e o desempenho de ovinos, arraçoados com dietas isoproteicas, contendo 75% de resíduos da agroindústria frutífera (abacaxi, acerola, maracujá e cupuaçu), uma dieta com feno de tifton e 25% de concentrado, em delineamento inteiramente ao acaso. A participação do resíduo de maracujá na dieta proporcionou os maiores níveis de consumo de matéria seca (1170,6g d-1) em relação aos resíduos de abacaxi (693,8g d-1), acerola (644,2g d-1), cupuaçu (452,9g d-1) e feno de tifton (962,7g d-1), o que se relaciona aos seus níveis de digestibilidade (77,8; 63,1; 59,1; 61,7 e 71,8%, respectivamente). Tal resultado gerou diferenças significativas, destacando-se o resíduo de maracujá quanto à conversão alimentar (8,3), e o ganho médio diário de peso (141,5g d-1). Apesar de ter tido a mesma conversão observada para o feno de tifton (13,2), apresentou maior ganho médio diário (75,6g d-1). Os demais resíduos apresentaram efeitos sobrepostos, contudo o resíduo de acerola ficou com a pior conversão (51,4) e o menor ganho médio diário (15,6g d-1), sendo esse sem diferença em relação ao cupuaçu (23,0g d-1). Os resíduos podem ser utilizados como alternativa para a alimentação de ovinos.

Ovarian tissue cryopreservation has been widely investigated for preserving female fertility. In the present study, we aimed to compare the effects of three concentrations (1, 1.5, and 3 M) of dimethylsulfoxide (DMSO) on the vitrification of ovarian tissue. The ovarian cortex was divided into control and vitrified groups: (i) 1 M-DMSO, (ii) 1.5 M-DMSO, and (iii) 3 M-DMSO. Follicles from all fragments were analyzed for DMSO-induced deleterious effects, morphological and morphometric aspects, and concentration of reactive oxygen species. Additionally, the fragments were cultured to assess the integrity and return of follicular development post-vitrification. All DMSO concentrations resulted in a higher percentage of degenerated preantral follicles than before the cryopreservation process. After vitrification, the cryopreserved ovarian fragments showed similar percentages of intact follicles; however, the 3 M DMSO concentration differed from the control. Analyzing free radical production, we found that the 3 M DMSO concentration had higher levels of oxidative stress than the lower DMSO. After in vitro cultivation of the vitrified/warmed fragments, the 1 M DMSO concentration exhibited higher percentages of morphologically intact follicles than the other concentrations. Therefore, we suggest that bovine preantral follicles can be cryopreserved in situ with greater efficiency in 1 M DMSO.