Effect of Disaccharide Inclusion in Vitrification and Warming Solutions on Developmental Competence of Vitrified/Warmed Germinal Vesicle Stage Buffalo Oocytes

BACKGROUND

Cryopreservation of immature oocyte is a potential strategy for preserving the female germline, providing a non-seasonal, easily accessible source for reproduction and science. Exposure of oocytes to high concentrations of cryoprotectants during vitrification is toxic and can negatively impact the fertilization ability and development of vitrified/warmed oocytes.

OBJECTIVE

1) to evaluate the effects of exposure of buffalo germinal vesicle (GV) oocytes to different vitrification solutions (VS), either supplemented with or without sucrose, on cumulus expansion and nuclear maturation following IVM; and 2) to compare the effects of sucrose and trehalose in the warming solution on developmental competence of buffalo oocytes vitrified at the GV-stage.

MATERIALS AND METHODS

Cumulus oocyte complexes (COCs) obtained at slaughter from mature buffalo ovaries were randomly assigned into five groups: control - directly subjected to IVM); VS1 group - exposed to 20% ethylene glycol (EG) + 20% glycerol (GLY) + 0.5 M sucrose; VS2 group - exposed to 20% EG + 20% GLY; VS3 group - subjected to 20% EG+20% dimethyl sulfoxide (DMSO) + 0.5 M sucrose; and VS4 group - subjected to 20% EG+20% DMSO. Following cryoprotectant dilution, viable oocytes were matured in vitro for 22 h; cumulus expansion and nuclear maturation were then evaluated (Experiment 1). COCs were vitrified by solid surface vitrification (SSV) in a solution composed of 20% EG + 20% DMSO (VS4). Following vitrification, COCs were warmed in a solution composed of either sucrose or trehalose in decreasing concentrations (1 M, 0.5 M and 0.25 M). Morphologically viable oocytes were matured, fertilized and cultured in vitro. Cleavage and blastocyst rates were evaluated at 30 h and day 7 post-insemination (p.i.), respectively (Experiment 2).

RESULTS

Exposure of GV-buffalo oocytes to different cryoprotectant combinations did not significantly affect cumulus expansion following IVM. However, nuclear maturation rate (oocytes at MII) was significantly higher (P<0.05) in the groups exposed to sucrose-free vitrification solutions (VS2 and VS4) and not significantly different from the control. Compared with the control group, the cleavage and blastocyst rates were significantly (P<0.05) lower in oocytes vitrified and then warmed in a solution containing trehalose; whilst this was not the case when sucrose was present in the solution.

CONCLUSION

Our results suggest that exposure of buffalo GV-oocytes to sucrose-free vitrification solutions improved nuclear maturation after IVM. Moreover, warming of vitrified buffalo oocytes in sucrose-based solution improved preimplantation development following IVM and IVF compared to trehalose based media.

Seasonal variation in testicular blood flow dynamics and their relation to systemic and testicular oxidant/antioxidant biomarkers and androgens in rams

The environmental temperature increased during summer and decreased during winter to the limits that might negatively affect animal and human reproduction. The responses of Egyptian rams to either hot or cold climatic conditions were studied in six mature rams subjected to weekly testicular Doppler ultrasonographic examination, blood sampling, seminal plasma collection and semen evaluation. The maximum environmental temperature and the relative humidity were used to classify the climatic condition according to the heat stress equation of sheep into hot months where temperature-humidity index (THI) was >26 (31.67 ± 0.54), and cold months where THI was <22 (18.39 ± 0.41). Testosterone, estradiol, superoxide dismutase (SOD), glutathione peroxidase (GPX) and lipid peroxide product (malondialdehyde, MDA) were measured in both blood and seminal plasma, while catalase (CAT) and reduced glutathione (GSH) were measured in blood and seminal plasma, respectively. Results revealed that, during the hot months, rams displayed significantly decreased testicular blood flow, increased seminal plasma MDA, decreased seminal plasma (SOD, GPx and GSH) and blood CAT antioxidant enzymes. The present study evidenced two novel findings: (a) the marked decrease in testicular blood flow volume, that is remarkable increase in both resistive index (RI) and pulsatility index (PI) values, during hot months could be negatively affected both seminal plasma enzymatic activities and seminal attributes, and (b) the SOD and GPx activities in seminal plasma of such animals were suitable predictive markers for seminal attribute evaluation.

A review of reproduction in the female camel (Camelus dromedarius)

The Arabian camel (Camelus dromedarius), the one-humped camel, is a primary inhabitant of the northern half of Africa, the Middle East and Pakistan and India. The dromedary is a multipurpose animal used for transportation, the production of milk and meat, as well as such by-products as wool, hair and hides. Dromedaries are extremely well adapted to their hot, arid environment. Consequently, Arabian camels are of considerable economic importance. Relatively little attention has been paid to the breeding of dromedaries. In the literature, particularly that in the English language, information on reproduction in the dromedary tends to be fragmentary. This review consolidates several widely scattered reports as projected against the author's own experience. It is hoped that the information is of particular help for those in charge of the breeding of dromedaries in zoological gardens and animal parks in countries where the one-humped camel is a rare species.