Effects of estrous cycle stage and transport temperature of ovaries on in vitro maturation of canine oocytes.

Unlike other domestic animals, in vitro maturation (IVM) of canine oocytes still has limited success. The present study investigated the effects of estrous cycle stage and transport temperature of ovaries on in vitro maturation of canine oocytes. The donor bitches were categorized into three groups based on stage of estrus cycle: follicular (proestrus or estrous), luteal (diestrus) and anestrus. One ovary of each pair collected from 39 mature bitches was transported in Phosphate Buffer Saline (PBS) at 4 degrees C while the other was transported at 37 degrees C. A total of 1138 Grade I COCs obtained from all ovaries were grouped and matured in modified synthetic oviduct fluid (mSOF) supplemented with follicle stimulating hormone (FSH), luteinizing hormone (LH), essential and non-essential amino acids at 38.5 degrees C in a humidified 5% CO(2), 5% O(2), and 90% N(2) atmosphere for 72 h. The nuclear maturation rates were evaluated by aceto-orcein staining. Oocytes harvested from follicular and luteal ovaries have a significantly higher maturation rates (MI+MII) than the oocytes from anestrual ovaries in the 37 degrees C group (p<0.05). However, oocytes harvested from anestrual ovaries transported at 4 degrees C had the highest maturation (MI+MII) rate, and the difference between anestrual and luteal ovary groups was significant (p<0.05). The oocytes from anestrual ovaries transported at 4 degrees C have significantly higher maturation rates than those transported at 37 degrees C (p<0.0001). However, the transport temperature (37 or 4 degrees C) did not significantly affect the maturation (MI+MII) rates of oocytes harvested from the luteal (p=0.61) and follicular (p=0.48) stage ovaries. It can be concluded from this study that (1) both transport temperature and transport temperaturexestrus cycle stage interaction effected the maturation rates, while estrus cycle stage alone did not, and (2) transporting canine ovaries at 4 degrees C can improve in vitro maturation rates in oocytes harvested from anestrous ovaries.

Developmental competence of domestic cat oocytes from ovaries stored at various durations at 4 degrees C temperature.

Temporal storage of ovaries can provide opportunity to rescue oocytes from ovaries of endangered felids. The objective of the study was to examine the effect of different storage periods (2, 24 and 48h) of ovaries at 4 degrees C for maturation of cat oocytes in vitro. Ovaries were collected from 25 domestic cats at various stages of the estrous cycle by routine ovariohysterectomy following anesthesia at different local veterinary clinics, and maintained in physiological saline at 4 degrees C for 2, 24 or 48h until oocytes recovery. Selected COCs were maturated at 38 degrees C for 48h in four-well petri dishes, which included 500microL modified synthetic oviduct fluid (mSOF) medium under mineral oil in a humidified 5% CO(2), 5% O(2), and 90% N(2) atmosphere incubator. After the in vitro maturation period, there were no differences between the rate of oocytes matured at MII stages in 2 and 24h storage groups (50.7% and 48.2% respectively, p>0.05). However, the same result for the 48h group was significantly lower than the 2 and 24h groups (28.0%, p<0.001). Our results suggest that while 2 or 24h storage of ovaries at 4 degrees C does not affect the meiotic competence of oocytes in vitro, 48h storage of ovaries decrease the results dramatically.

Effect of transport and storage temperature of ovaries on in vitro maturation of bitch oocytes.

In this study, the effects of ovary transport and storage temperature on in vitro maturation of bitch oocytes were investigated. Ovaries were collected from 23 mature bitches and one randomly selected ovary of each pair (n=23 pairs) was transported in physiologic saline at 4 degrees C, while the other one at 35-38 degrees C for 2-4h. A total of 316 cumulus oocyte complexes (COCs) were obtained from the 4 degrees C group and 301 COCs from the 35-38 degrees C group. All COCs were matured in modified synthetic oviduct fluid (mSOF) supplemented with follicle stimulating hormone (FSH), essential and non-essential amino acids at 38 degrees C in a humidified 5% CO2, 5% O2, and 90% N2 atmosphere for 72 h. At the end of the in vitro maturation period, nuclear maturation of oocytes was classified as germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase I (MI), metaphase II (MII), undetermined nuclear maturation (UDNM), and MI+MII. The nuclear maturation rates to MI, MII, and MI+MII stages were 60.44%, 10.75%, and 71.20% in the 4 degrees C group and 37.20%, 7.64%, and 45.85% in the 35-38 degrees C group, respectively. The data demonstrated that oocytes obtained from ovaries transported at 4 degrees C had higher maturation rates than from the ones transported at 35-38 degrees C (p<0.001).