Ultrastructure and cell death of in vivo derived and vitrified porcine blastocysts.

Morphological and molecular signs of injury and cell death and subsequent regeneration following vitrification of porcine blastocysts were evaluated by light (LM) and transmission electron microscopy (TEM) as well as TUNEL/propidium iodide (PI) nuclear staining followed by confocal microscopy (CSM). In vivo derived blastocysts were assigned to one of the following four groups: Controls-(1) fixed immediately after collection (C0h) and (2) after 24 hr culture in vitro (C24h) and vitrified embryos-(3) fixed immediately after vitrification and warming (V0h), and (4) after 24 hr of culture upon warming after vitrification (V24h). Observation by LM and TEM showed that the V0h embryos displayed collapse of the blastocoele cavity (BC) and cell swelling, a general distension or shrinkage of mitochondria and massive increase in the amount of vesicles, vacuoles, and secondary lysosomes (SLs). Approximately 2/3 of the V24h embryos had recovered, whereas the remaining 1/3 were degenerated. Recovered embryos displayed almost normal blastocyst morphology, except for a widening of the perivitelline space, accumulation of debris and partial distension of mitochondria, whereas degenerated embryos were disintegrated into a poorly defined mass of cells and debris including cells with abundant degeneration of mitochondria and other organelles. Both recovered and degenerated embryos displayed a persistent abundance of presence of small membrane bounded vesicles, vacuoles, and SLs. Evaluation of TUNEL/PI stained embryos showed only occasional appearance of TUNEL positive nuclei with typical apoptotic morphology in controls (C0h 0.67%, C24h 1.22%) and in the V0h embryos (0.93%). The percentage of apoptotic nuclei in embryos at V24h was significantly higher than in all other groups (2.64%). Vitrified embryos showed significantly increased appearance of DNA fragmented nuclei without typical morphological features of apoptosis (V0h 1.43%, V24h 4.30%) compared with controls (C0h 0.26%, C24h 0.45%). The observed morphological changes and increased DNA fragmentation observed immediately after vitrification and warming probably reflects a direct damaging effect of vitrification. During 24 hr of culture a portion of the embryos was able to regenerate and along with the regenerative process, apoptosis--a possible pathway for elimination of damaged cells--became evident.

In vitro development following one-step dilution of OPS-vitrified porcine blastocysts.

The objective of this experiment was to compare the in vitro survival and hatching rates of OPS-vitrified porcine blastocysts obtained after conventional (three-step dilution) or direct (one-step dilution) warming procedures. Expanded blastocysts were collected by laparotomy from weaned crossbred sows (n=7) on Day 6 of the cycle (D0: onset of estrus). Vitrification was performed as described by Berthelot et al. [Cryobiology 41 (2000) 116] using 17% (v/v) ethylene glycol and 17% (v/v) dimethyl-sulfoxide in the second vitrification medium. Conventional warming was carried out by plunging straws containing embryos in 800 microl of TCM199 Hepes containing 20% new born calf serum (TCM-NBCS) and 0.13 M sucrose for 1 min. Embryos were then transferred to another well with the same medium for 5 min, washed in TCM-NBCS with 0.075 M sucrose for 5 min and transferred to TCM-NBCS for 5 min. In one-step dilution, embryos were placed in 400 microl TCM-NBCS containing 0.13 M sucrose. To evaluate in vitro development, embryos warmed by conventional (n=59) or direct (n=58) procedures were cultured for 96 h. Non-vitrified embryos were used as controls (n=20). No significant (P>0.05) differences were observed in the in vitro development of vitrified and non-vitrified embryos. The survival and hatching rates obtained by three-step dilution (84.8 and 71.2%, respectively) and one-step dilution (86.2 and 74.1%, respectively) procedures were not different (P>0.05). The average diameter of expanded blastocysts from each donor was significantly different (P<0.001) among embryo donors. The embryo diameter or the interactions among the factors evaluated did not affect (P>0.05) the embryo survival and hatching of the vitrified/warmed blastocysts. However, the donor of embryos had a significant effect (P<0.001) on these parameters, confirming previous experiments. This experiment shows that porcine embryo vitrification and one-step dilution are promising procedures to be used under field conditions. However, the good results obtained in vitro must be confirmed also by in vivo experiments.

Vitrification of porcine embryos at various developmental stages using different ultra-rapid cooling procedures.

In this study, three different vitrification systems (open pulled straw: OPS; superfine open pulled straw: SOPS; and Vit-Master technology using SOPS: Vit-Master-SOPS) were compared in order to investigate the influence of cooling rate on in vitro development of vitrified/warmed porcine morulae, early blastocysts, or expanded blastocysts. Embryos were obtained surgically on Day 6 of the estrous cycle (D0 = onset of estrus) from weaned crossbred sows, classified and pooled according their developmental stage. A subset of embryos from each developmental stage was cultured to evaluate the in vitro development of fresh embryos; the remaining embryos were randomly allocated to each vitrification system. After vitrification and warming, embryos were cultured in vitro for 96 h in TCM199 with 10% fetal calf serum at 39 degrees C, in 5% CO(2) in humidified air. During the culture period, embryos were morphologically evaluated for their developmental progression. The developmental stage of embryos at collection affected the survival and hatching rates of vitrified/warmed embryos (P < 0.001). The vitrification system or the interaction of vitrification system and developmental stage had no effect on these parameters (P > 0.05). Vitrified expanded blastocysts showed the best development in vitro (P < 0.001), with survival and hatching rates similar to those of fresh expanded blastocysts. The hatching rate of fresh morula or early blastocyst stage embryos was higher than their vitrified counterparts. In conclusion, under our experimental conditions, cooling rates greater than 20,000 degrees C/min, as occurs when SOPS or Vit-Master-SOPS systems are used, do not enhance the efficiency of in vitro development of vitrified porcine embryos.

Characterization of human CD55 and CD59 transgenic pigs and kidney xenotransplantation in the pig-to-baboon combination.

New transgenic pigs expressing combinations of regulators of complement activation and other molecules are needed to resist xenograft hyperacute rejection (HAR) and to further analyze and treat xenograft rejection. Double transgenic pigs for human CD55 (hCD55) and human CD59 (hCD59) using the promoter of the human elongation factor 1 alpha gene were generated, and their kidneys were transplanted into nonimmunosuppressed baboons. hCD55 and hCD59 were mainly expressed by the endothelial cells, and these cells showed increased resistance to complement-mediated lysis. Baboons receiving kidneys from hCD55hCD59 pigs survived for 5 and 6 days, and displayed alterations in coagulation. Thrombocytopenia and platelet microthrombi were present within the kidneys. Nontransgenic kidneys showed HAR in less than 2 days. Kidneys from pigs expressing hCD55hCD59 displayed protection against HAR in the absence of immunosuppression. Rejection was associated with coagulopathy leukocyte infiltration and a rebound of anti-alpha Gal antibodies.

Transfer of vitrified blastocysts from one or two superovulated Large White Hyperprolific donors to Meishan recipients: reproductive parameters at Day 30 of pregnancy.

The present study was designed to determine the effect of pooling embryos from two donors on the reproductive success of transfer of vitrified/warmed porcine blastocysts. Intact blastocysts were collected from superovulated Large White Hyperprolific gilts (n = 24) on Days 5-5.5 after artificial insemination. Embryos were recovered by flushing the uterine horns, and unhatched blastocysts were selected. Vitrification and warming were performed as described by Berthelot et al. [Cryobiology 41(2000) 116]. To evaluate in vitro development, 37 vitrified/warmed blastocysts were cultured, non-vitrified embryos (n = 48) were used as controls. Embryo transfers were conducted in asynchronous (-24 h) Meishan gilts (n = 20). Twenty vitrified/warmed blastocysts were surgically transferred into one uterine horn. Ten recipients received embryos from one donor (Group 1) and the other 10 transfers were performed with mixed embryos from two donors (Group 2). Pregnancy was assessed ultrasonographically at Day 25 after estrus and recipients were slaughtered at Day 30 after transfer. In vitro survival rate of the vitrified/warmed blastocysts was lower (P < 0.01) than that from control embryos (73.0% versus 93.7%). The pregnancy rate for Group 1 (70%) was not different (P > 0.05) than that from Group 2 (90%). No significant differences were detected between Groups 1 and 2 for in vivo embryo development (number fetuses/transferred embryos in pregnant recipients) or in vivo embryo survival (number viable fetuses/transferred embryos in pregnant recipients). However, the in vivo efficiency (number viable fetuses/total transferred embryos) was higher (P < 0.05) when transfers were performed with embryos from two donors (19.5% versus 30.5%). These results indicate that pooling embryos from two donors increases the in vivo efficiency after transfer of vitrified/warmed porcine blastocysts.

Determination by echography of uterine changes around puberty in gilts and evaluation of a diagnosis of puberty.

Three experiments were carried out to evaluate the use of ultrasonography in assessing the onset of puberty in gilts. In experiment 1, gilts (n = 17) were scanned 3 times per week beginning at 133 and continuing until 187 days of age. The ultrasonic appearance of the uterus was described, quantified and compared with the reproductive status observed at slaughter. The quantification of the pictures showed a different correlation in time for infantile, impubertal, prepubertal and pubertal stages. For pubertal females, "uterine area" increased at around 180 days of age, well-defined sections of the uterine horns appeared 3 +/- 0.5 days before puberty. In infantile and impubertal gilts during the same period of age, uterine images remained dark and homogeneous; no significant change in the "uterine area" was observed. This difference in images allowed an evaluation of the diagnosis of puberty. In experiment 2, the gilts (n = 123) were scanned, the result was verified at slaughter the day after by examination of the genital tract. The uterine weight of the gilts that had reached a prepubertal or pubertal stage was significantly greater (P = 0.0001) than that in impubertal gilts. The sensitivity and the specificity of the diagnosis were 91.9% and 96.5% respectively. Experiment 3 was performed on a farm and echographic examinations were carried out one and five days after gilts (n = 117) arrived at the piggery. Oestrus detection or blood sampling for progesterone determinations were used as tools to determine the reproductive status. The sensitivity and the specificity of the diagnosis were 98.9% and 100% respectively. This diagnosis of puberty is thus accurate.