Effects of storing pig ovaries at 4 or 20 degrees C for different periods of time on the morphology and viability of pre-antral follicles

Effects of storing queen ovaries in saline solution at 22 C on ovarian follicle integrity and oocyte quality and maturation

This study evaluated the effects of storing queen ovaries in saline at 22 °C for up to 12 h. Two experiments were conducted. In the first experiment, ovaries from five queens were sectioned into four fragments; stored for 4, 8, or 12 h; and histologically analyzed to assess follicular morphology (Grades I-IV). In the second experiment, ovaries from 15 additional queens were stored under the same conditions, after which cumulus-oocyte complexes (COCs) were retrieved and graded (I-IV); only Grades I and II underwent in vitro maturation to assess cumulus expansion and meiotic status. The effects of storage on follicle morphology, COC quality, and maturation were analyzed using the chi-square test, while Spearman's correlation assessed the relationship between storage time and follicle morphology. The results showed that early-stage follicles were more sensitive to short-term storage, with 56 %, 22 %, 2 %, and 0 % of primordial, primary, secondary, and antral follicles, respectively, classified as Grade IV after 4 h. Grade I follicles declined to 0 % across all developmental stages after 12 h. Significant correlations were found between storage duration and follicle morphology (Grade I: r = -0.92, Grade II: r = -0.65, Grade III: r = 0.68; P < 0.05), while Grade IV remained unchanged. COC recovery did not differ across storage times (P > 0.05), with >60 % classified as Grade III or IV at all time points. After 12 h, there was a significant reduction in Grade I COCs, cumulus expansion, and the percentage of oocytes reaching metaphase II (P < 0.05). In conclusion, while storing queen ovaries in saline at 22 °C negatively affects follicular morphology - particularly preantral follicles - oocytes can still be recovered up to 8 h post-storage, without compromising COC quality or maturation potential.

Ovarian tissue transportation: a systematic review

In recent years, some countries and fertility preservation networks have started adopting 24 h transportation for ovarian tissue, a practice that has the potential to spread very quickly due to the high costs and bureaucracy involved in the establishment of ovarian tissue cryobanks. While pregnancies and live births have been reported after such long periods of transportation, this, however, remains an empirical procedure. This review aims to prompt reflection on ovarian tissue transport, highlighting the lack of knowledge in humans by providing a counterpoint looking into more than 40 studies published in different animal models. By discussing these studies in animals, the findings of various models can be deciphered, and light shed on the patterns identified. Like the development of different assisted reproductive technology procedures, this is an important step in creating guidelines for future studies on human ovarian tissue transportation.

Evidence of metabolic activity during low-temperature ovarian tissue preservation in different media

PURPOSE

Although ovarian tissue transportation has been validated for up to 24 h, there is no standard protocol to date. We aimed to elucidate how existing media currently used for ovarian tissue transportation affect ovarian tissue metabolism and cell viability.

METHODS

Cow ovarian fragments were immersed in 0.9% NaCl solution, IVF medium, Leibovitz 15 medium (L-15), or PBS for 1, 4, or 24 h at 4 °C. Media were analyzed for pH, lactate dehydrogenase (LDH) activity, and glucose, pyruvate, and lactate concentrations, while apoptosis was assessed by TUNEL assays in fixed fragments. Viability rates were assessed by flow cytometry (FACS).

RESULTS

There were lower pH levels in NaCl at all time points compared with other media. LDH activity increased with time and was lowest in NaCl at 1 and 4 h. There was no significant difference in glucose levels, but a significant pyruvate decrease in L-15 and a significant lactate increase in all media. TUNEL showed apoptosis rates ranging from 0 to 5%. FACS showed a mean of 4% necrotic cells and 15-19% apoptotic cells after 1 h of incubation, but less than 1% necrotic cells and 2-6% apoptotic cells after 24 h in all media.

CONCLUSION

Our results indicate marked metabolic activity in ovarian tissue at 4 °C and suggest that cells use internal sources of energy, which may influence transplantation outcomes. This highlights the importance of better understanding whole tissue dynamics to develop a standard protocol for ovarian tissue transportation. Graphical abstract.

Reproductive technologies in swine

This chapter highlights the importance of reproductive technologies that are applied to porcine breeds. Nowadays the porcine industry, part of a high technological and specialized sector, offers high-quality protein food. The development of the swine industry is founded in the development of breeding/genetics, nutrition, animal husbandry, and animal health. The implementation of reproductive technologies in swine has conducted to levels of productivity never reached before. In addition, the pig is becoming an important species for biomedicine. The generation of pig models for human disease, xenotransplantation, or production of therapeutic proteins for human medicine has in fact generated a growing field of interest.

Short-term preservation of Pecari tajacu ovarian preantral follicles using phosphate buffered saline (PBS) or powdered coconut water (ACP(r)) media

We compare protocols for the short-term preservation of collared peccarie's ovarian preantral follicles (PFs) by using phosphate buffered saline- (PBS) or powdered coconut water- (ACP(r)) based medium. For morphology analysis each pair of ovaries collected from six females was divided into nine fragments. One fragment was destined for morphology analysis (histology and transmission electron microscopy - TEM), constituting the control group and the other fragments were placed in tubes with PBS or ACP(r), packed in 5 L Styrofoam boxes, stored for 4h, 12h, 24h, and 36h, and then analyzed. For viability analysis a pair of ovaries from two additional females was divided into nine fragments; one fragment was immediately destined for viability analysis (Trypan blue test) and the other fragments were stored as previously described, until 24h and then analyzed. After 4h storage in ACP(r) medium, the follicular integrity was similar to control (87.8% vs 94.4%, respectively); however, ultrastructural analyses revealed swollen mitochondria as the first signals of PF degeneration. It was observed that ACP(r) (66.7%) was more efficient than PBS (49.4%) to preserve the morphological integrity after 36h storage (P<0.05); however, no differences were observed on follicular viability (P>0.05). In conclusion, the use of the ACP(r) is recommended for the short-term preservation of Pecari tajacupreantral follicles.

Short-term preservation of canine preantral follicles: Effects of temperature, medium and time

The use of the large pool of preantral follicles is a promising alternative to provide high numbers of fertilizable oocytes to reproductive biotechnology. This issue is particularly important to canids, since current rates of success of in vitro techniques using oocytes are very limited, and many species within this family are threatened by extinction. The aim of this study was to evaluate effects of temperature, medium and time on morphology and viability of canine preantral follicles during short-term preservation. Canine ovaries were cut into fragments which were incubated in 0.9% NaCl solution or in minimum essential medium (MEM) at 4, 20 or 38 degrees C for 2, 6, 12 or 24 h. Afterwards, preantral follicles were analyzed by histology, transmission electron microscopy and viability testing using trypan blue, calcein-AM and ethidium homodimer-1. Percentages of morphological normal and viable follicles were maintained similar to control (time 0 h) after incubation in 0.9% NaCl at 4 or 20 degrees C for up to 6h and at 38 degrees C for 2 h. Using MEM, such preservation was possible for 12h at 4 or 20 degrees C, and for 6h at 38 degrees C. These results indicate that preservation of canine preantral follicles might be better accomplished through hypothermic (4 or 20 degrees C) storage in MEM, which ensures maintenance of morphology and viability for up to 12h.

Chilling ovarian fragments during transportation improves viability and growth of goat preantral follicles cultured in vitro

The aim of the present study was to evaluate the effects of storage of goat ovarian fragments at different temperatures and for different incubation times on the viability and growth of cultured preantral follicles in vitro. Caprine ovaries were collected and divided into 19 fragments, with one fragment being fixed immediately (fresh control). The remaining fragments were placed in minimal essential medium (MEM) and maintained at 4, 20 or 35°C for 2 or 4 h. After each incubation period, some of the fragments were fixed (non-cultured), whereas others were cultured in vitro for 1 or 7 days. Fragments were processed to enable routine histological and transmission electron microscopic examination. After 7 days of culture, only ovarian fragments stored at 4°C for 4 h maintained a percentage of morphologically normal follicles similar to that in the fresh control. For all other treatments groups, there was a significant increase in follicular activation observed. In addition, there was an increase in oocyte and follicular diameter after culture of ovarian cortex that had been chilled previously at 4°C for 2 or 4 h. In conclusion, the present study demonstrated that chilling ovarian fragments at 4°C during transportation is best for maintaining follicle viability and to increase follicular growth during in vitro culture.