Effect of different types of cryoprotectants on developmental capacity of vitrified-thawed immature buffalo oocytes

The study aimed to determine the effects of different types of cryoprotectants on developmental capacity of vitrified-thawed immature buffalo oocytes. The vitrification solution [VS] consisted of Dulbecco's phosphate buffered saline [DPBS] supplemented with 0.5 M sucrose, 0.4% bovine serum albumin [BSA] and different types of molar [M] concentrations of the cryoprotectants which composed of either glycerol [G], ethylene glycol [EG] or dimesthyl sulfoxide [DMSO] in order to determine the best type of vitrification cryoprotectants. The concentrations tested were 4 M, 7 M and 7M concentration of G, EG and DMSO, respectively. Cumulus oocyte complexes [COCs] were obtained from slaughterhouse ovaries. Oocytes were vitrified immediately after collection .The COCs were pre-equilibrated in 50% of the VS for 3-5 min, then kept in VS for 1 min and loaded in pre-sterilized 0.25 ml straws for 7-10 days of storage in liquid nitrogen. The straws were thawed in warm water at 37°C for 10 seconds and COCs were evaluated for morphological damage. Morphologically normal COCs were cultured in vitro and evaluated for maturation. Oocytes were fertilized with frozen-thawed semen capacitated in Brackett and Oliphant [BO] medium contained heparin and caffeine and evaluated for cleavage and embryonic development. The results revealed that the proportion of buffalo oocytes found to be morphologically normal was significantly [p<0.05] higher in EG and DMSO than those obtained in G [85.0 and 83.33 vs 65.0%, respectively]. Among the damaged oocytes, cracking of zona pellucida was the most frequent abnormality observed. A significantly higher [p<0.05] percentage of maturation and cleavage rates derived from vitrified -thawed immature oocyte in EG and DMSO than those obtained in G [47.05, 46.67%; 28.57, 25.71 vs 30.76% and 10.0%, respectively]. A similar trend was observed in blastocyst stage produced in vitro. However, in vitro developmental competence was higher for vitrified-thawed fresh oocytes [control] than those obtained from all groups of cryoprotectants. that 7M solution of EG or DMSO could be used for vitrification of immature buffalo oocytes for their subsequent utilization in the in vitro maturation, fertilization and embryo production

effect of progesterone on the in vitro maturation and developmental competence of mouse germinal vesicle oocytes

The aim of the present study was to investigate the role of progesterone on the developmental competence of cumulus-oocyte complexes [COCs] and cumulus-denuded oocytes [CDOs] at germinal vesicle [GV] stage. GV oocytes of pregnant mare's serum gonadotropin [PMSG]-primed prepubertal mice were divided into two groups: CDOs and COCs. The oocytes were cultured in TCM199 with different concentrations of progesterone [10, 38, 50 and 100 micro M] and without progesterone [controls]. The number of oocytes at the GV, germinal vesicle breakdown [GVBD] and metaphase II [MII] stages were counted. In vitro fertilization [IVF] of MII oocytes and their development to the blastocyst stage were evaluated. Significantly different MII rates were observed between the COCs [85%] and CDOs [68%] control groups. The MII rates of 83%, 48%, 14% and 0% for COCs and 65%, 53%, 20% and 0% for CDOs were obtained in TCM199 that contained 10, 38, 50 and 100 micro M progesterone concentrations, respectively. These MII rates were lower [p<0.05] in both COCs and CDOs as compared to their respective control groups, except for 10 micro M. The fertilization and blastocyst rates of COCs [83% and 35%, respectively] were higher [p <0.05] than those of the CDOs [51% and 5%, respectively] control groups. The fertilization and blastocyst rates in the presence of 10 micro M [81% and 36%, respectively] and 38 micro M [85% and 30%, respectively] progesterone in COCs and CDOs [52% and 4% for 10 micro M; 56% and 4% for 38 micro M] were similar to their respective control groups. Adding progesterone to the medium could not improve maturation of mouse GV oocytes and their development to the blastocyst stage

[Effects of different doses of LIF on IVM rate and cumulus expansion in mouse oocytes]

The aim of this research was to study the effects of different doses of LIF on GVBD and MII development rate and cumulus expansion. Immature mice superovulated with HMG and GV oocytes obtained from ovary 48 hours later. The GV oocytes were cultured in TCM199 with 100, 500 and 1000 RI /ml LIF. Cumulus expansions were evaluated with two examiners and numbers of MII oocytes were recorded. For denuding the oocytes hyaloronidase was used. Our results showed that the rate of GVBD and MII development increased in -groups with LIF compared with control group. Rate of MII development with 1000 IU/ml LIF was significantly higher than that of control group [P<0.05]. Cumulus expansion in group with 1000 IU/ml LIF improved significantly compared with control group [p<0.05]. Our results showed that LIF could improve IVM rate in dose dependant. Also cumulus expansion improved in group with LIF and increased oocyte quality