49 PRACTICAL APPLICATION OF THE HOLLOW FIBER VITRIFICATION METHOD FOR CRYOPRESERVATION OF MAMMALIAN EMBRYOS

2014 ◽  
Vol 26 (1) ◽  
pp. 138 ◽  
Author(s):  
A. Uchikura ◽  
T. Wakayama ◽  
S. Wakayama ◽  
H. Matsunari ◽  
M. Maehara ◽  
...  

We recently developed the hollow fibro vitrification (HFV) method, which is a novel, high-performance embryo cryopreservation method (Matsunari et al., 2012). In this study, we aimed to verify the applicability of the HFV method for cryopreserving various types of embryos; BDF1 mouse embryos at the 2-cell stage, porcine parthenogenetic morulae derived from in vitro-matured oocytes, bovine morulae produced by in vitro maturation/fertilization (LIAJ Animal Biotechnology Center, Tokyo, Japan), and in vivo-derived blastocysts of common marmosets were vitrified, and their survival was assessed by culture or transfer. The embryos were vitrified using 20 mM HEPES-buffered TCM-199 containing 20% calf serum as a base medium. Cellulose acetate hollow fibres (25 mm) containing 1 to 20 embryos were placed in an equilibration solution containing 7.5% ethylene glycol (EG) and 7.5% dimethyl sulfoxide (DMSO) for 5 to 7 min, followed by incubation for 1 min in vitrification solution containing 15% EG, 15% DMSO, and 0.5 M sucrose. The embryos were then vitrified by immersion in LN. The embryos were devitrified by immersing the hollow fibre in a 1 M sucrose solution at 38.5°C, which was followed by stepwise dilution of the cryoprotectants and washing. For a subset of the vitrified mouse embryos, rewarming in a non-ultra-rapid manner by melting a hollow fibre in air at room temperature for 5 s was tested. Embryo transfer was performed to assess the viability of the vitrified mouse embryos. For porcine embryos, vitrification in LN vapor (–150°C) was tested. Development of the vitrified mouse embryos to blastocysts was equal to that of the non-vitrified embryos [105/110 (95.5%) v. 109/110 (99.1%)]. Post-transfer development to fetuses was also equal between the vitrified and non-vitrified embryos [pregnancy rates: 4/4 v. 2/2; developmental rates: 55/80 (68.8%) v. 35/40 (87.5%)]. Non-ultra-rapid rewarming did not decrease the survival of the vitrified mouse embryos [blastocysts: 94/100 (94.0%); pregnancy: 4/4; fetuses: 55/80 (68.8%)]. Blastocyst formation was equivalent for vitrification of porcine embryos in LN vapor [27/34 (79.4%)], direct immersion into LN [28/35 (80.0%)], and the non-vitrified control [31/32 (96.9%)]. Vitrification of 191 bovine morulae resulted in 153 (80.1%) blastocysts. In preliminary experiments, survival of marmoset blastocysts was 100% (n = 6). These data demonstrate that the HFV method is (1) effective for embryos of various species and production methods; (2) effective even for porcine in vitro-derived morulae, which are highly cryosensitive; and (3) amenable to modifications such as non-ultra-rapid warming and cooling in LN vapor, increasing the potential applicability of the HFV method. For instance, vitrification in LN vapor may allow embryo cryopreservation with high hygienic standards. This study was supported by JST, ERATO, Nakauchi Stem Cell and Organ Regeneration Project.

1989 ◽  
Vol 1 (2) ◽  
pp. 127 ◽  
Author(s):  
D Sakkas ◽  
AO Trounson ◽  
I Kola

The cleavage rate and development of two-cell mouse embryos to the morulae stage in co-culture with mouse oviduct cells was studied in vitro and compared with those achieved in vivo. Embryos were cultured in Whittingham's T6 (T6), T6 supplemented with fetal calf serum (FCS) and in co-culture with either Dulbecco's Modified Eagles Medium supplemented with sodium lactate (DMEM + 1a) or a modification of T6 medium containing vitamins and amino acids (T6 + v + aa). Co-culture of oviductal cells with DMEM + la medium supported two-cell mouse embryo development to eight cells at a rate significantly better (P less than 0.001) than T6, but the rate of embryo development was not equivalent to that in vivo. DMEM + la alone was inadequate as an embryo culture medium. Co-cultures using T6 + v + aa with mouse oviductal cells were prepared from mice at days 1, 2 or 3 of pseudopregnancy. Day 2 and 3 co-cultures allowed two-cell embryos to develop at a rate comparable to that in vivo up to the mid eight-cell stage (68 h after hCG), but by 76 h after hCG embryos were retarded. Transfer to pseudopregnant recipients of embryos co-cultured with day 2 oviductal cells until 68 h after hCG resulted in a rate of fetal development equivalent to that of embryos grown in vivo. Our results show that co-culture of early cleavage-stage embryos with mouse oviductal cells allows embryos to retain cleavage rates and viability comparable to in vivo development.


2006 ◽  
Vol 18 (2) ◽  
pp. 157 ◽  
Author(s):  
K. Hiruma ◽  
H. Ueda ◽  
H. Saito ◽  
C. Tanaka ◽  
N. Maeda ◽  
...  

To date only in vivo-produced embryos have successfully produced live piglets after cryopreservation. In this study, we aimed to produce piglets from vitrified embryos derived from in vitro matured (IVM) oocytes. Cumulus-oocyte complexes collected from ovaries obtained at a local slaughterhouse were matured for 44 to 45 h in NCSU23 MEDIUM supplemented with 0.6 mM cysteine, 10 ng/mL epidermal growth factor, 10% (v/v) porcine follicular fluid, 75 �g/mL potassium penicillin G, 50 �g/mL streptomycin sulfate, and 10 IU/mL eCG/ hCG. These IVM oocytes were either activated for parthenogenesis or in vitro-fertilized (IVF). For IVF, oocytes were incubated with 5 � 106/mL of cryopreserved epididymal sperm in PGM-tac medium (Yoshioka et al. 2003 Biol. Reprod. 69, 2092-2099) for 20 h. Embryos were treated for removal of cytoplasmic lipid droplets (delipation; Nagashima et al. 1995 Nature 374, 416) at the 4- to 8-cell stages, around 50 to 54 h after activation or insemination. After culture in NCSU23 for 15 h, they were vitrified by the minimum volume cooling (MVC) method. Embryos were equilibrated with equilibration solution containing 7.5% (v/v) ethylene glycol (EG), 7.5% (v/v) dimethylsulfoxide (DMSO), and 20% (v/v) calf serum for 4 min, followed by exposure to vitrification solution containing 15% EG, 15% DMSO, 0.5 M sucrose, and 20% calf serum. Embryos were then loaded onto a Cryotop (Kitazato Supply Co., Tokyo, Japan) and immediately plunged into liquid nitrogen. Vitrified embryos were examined for viability in vitro and in vivo after warming. Their in vitro developmental competence was compared to that of corresponding control (nonvitrified) embryos. Vitrified 4- to 8-cell stage embryos, both parthenogenetic and IVF, showed developmental competence into blastocysts comparable to that of control embryos (parthenogenetic: 46.8%, 36/77 vs. 51.7%, 31/60; IVF: 40.0%, 30/75 vs. 44.3%, 35/79). Of four surrogate gilts that received a total of 251 vitrified parthenogenetic embryos, three became pregnant and had 20 fetuses (8.0%, 22 to 23 days old). Three surrogates gilts that received 267 vitrified IVF embryos all became pregnant. Of those, the one that received 47 embryos was confirmed to have eight fetuses (17.0%, 22 days old) by autopsy. The other two were examined by ultrasonography at 56 and 95 days of gestation and found to be pregnant. These results suggest that porcine embryos derived from IVM oocytes have a potential to develop into live offspring after delipation and MVC vitrification. This study was supported by PROBRAIN.


2006 ◽  
Vol 18 (2) ◽  
pp. 131
Author(s):  
K. Kaneyama ◽  
S. Kobayashi ◽  
S. Matoba ◽  
Y. Hashiyada ◽  
K. Imai ◽  
...  

Although many studies have been conducted on somatic cell nuclear transfer, there are only a few reports on cryopreservation of reconstructed embryos after nuclear transplantation. The objective of this study was to examine in vitro or in vivo development of vitrified blastocysts obtained by nuclear transfer. Nuclear transfer was carried out according to the procedure of Goto et al. (1999 Anim. Sci. J. 70, 243–245), and conducted using abattoir-derived oocytes and cumulus cells derived by ovum pickup from Holstein and Japanese Black cows. Embryos were vitrified as described by Saito et al. (1998 Cryobiol. Cryotech. 43, 34–39). The vitrification solution (GESX solution) was based on Dulbecco's PBS containing 20% glycerol (GL), 20% ethylene glycol (EG), 0.3 M sucrose (Suc), 0.3 M xylose (Xyl), and 3% polyethylene glycol (PEG). The blastocysts were equilibrated in three steps, with 10% GL, 0.1 M Suc, 0.1 M Xyl, and 1% PEG for 5 min (1); with 10% GL, 10% EG, 0.2 M Suc, 0.2 M Xyl, and 2% PEG for 5 min (2) and GESX solution (3). After transfer to GESX, equilibrated embryos were loaded to 0.25-mL straws and plunged into liquid nitrogen for 1 min. The vitrified blastocysts were warmed in water (20°C) and diluted in 0.5 M and 0.25 M sucrose for 5 min each. Equilibration and dilution procedures were conducted at room temperature (25–26°C). After dilution, the vitrified blastocysts were cultured in TCM-199 supplemented with 20% fetal calf serum and 0.1 mM β-mercaptoethanol at 38.5°C under gas phase of 5% CO2 in air. In Experiment 1, survival rates after vitrification were compared between the nuclear transfer and the IVF blastocysts. Survival rates of vitrified nuclear transfer blastocysts (n = 60, Day 8) at 24 and 48 h were 70.0% and 56.7%, respectively, and those of vitrified IVF blastocysts (n = 41) were 82.9% and 82.9%, respectively. There were no significant differences in survival rates at 24 and 48 h between the two groups. In Experiment 2, one (VIT-single) or two (VIT-double) vitrified and one (nonVIT-single) or two (nonVIT-double) nonvitrified reconstructed blastocysts per animal were transferred into Holstein dry cows. The result of Experiment 2 is shown in Table 1. This experiment demonstrated that the vitrification method in this study can be used for cloned embryo cryopreservation but the production rate should be improved. Table 1. Comparison of survival rates of vitrified or nonvitrified cloned embryos after transfer


2006 ◽  
Vol 18 (2) ◽  
pp. 154 ◽  
Author(s):  
G. Duchamp ◽  
F. Guignot ◽  
J. Grizelj ◽  
M. Vidament ◽  
P. Mermillod

In equine species, embryo cryopreservation is not as widely developed as in some other species. Slow freezing has been applied to equine embryos but with relatively low success rates. This higher sensitivity to conventional freezing procedures may be explained by the presence of a capsule surrounding the equine embryo that may impair cryoprotectant penetration. Recently, good in vitro embryo survival rate was obtained after open pulled straw (OPS) vitrification (Moussa et al. 2005 Theriogenology 64, 1619–1632). The aim of the present study was to evaluate in vivo survival of vitrified embryos five days after surgical transfer into Welsh pony mares. Morulae (M), early blastocysts (EB), and blastocysts (B) ranging from 140 to 320 μm in diameter were collected (n = 20) in a Ringer lactate solution on Day 6.75 after ovulation. Before vitrification, embryos were assessed morphologically and their size was measured (McKinnon and Squires 1988 J. Am. Vet. Med. Assoc. 192, 401–406). Then, embryos were vitrified using the OPS method described by Berthelot et al. (2001 Reprod. Nutr. Dev. 41, 267–272). Briefly, embryos were washed twice in HEMES-TCM-199 + 20% newborn calf serum (NBCS) for 1 min, equilibrated in HEPES-TCM-199 + 20% NBCS with 7.5% dimethyl sulfoxide (DMSO) + 7.5% ethylene glycol (EG) for 3 min, and then with 18% DMSO + 18% EG + 0.4 M sucrose for 45 s. One embryo was then loaded per straw. For transfer, four straws were quickly thawed (5 s in air) and the narrow end of the straw containing the embryo was immersed in HEPES-TCM-199 + 20% NBCS + PBS + 0.2 M sucrose. Five to 8 min after thawing, four embryos were surgically transferred into the cranial portion of the uterine horn in each of five pony mare recipients. Five days after transfer, embryos recovered by transcervical flushing of the uterus were classified as viable if morphology was normal, no dark inner cells were present, the capsule was intact, and the diameter was at least 1000 μm. The results are shown in the table. One recipient of vitrified embryos had an endometritis and no embryo was recovered. From the four other recipients, nine embryos were recovered out of 16 (56%) transferred, seven of which were viable (44%). The results of the present preliminary study demonstrating survival of equine embryos transferred after OPS vitrification is very encouraging. However, the results should be confirmed by birth of foals after transfer of OPS-vitrified embryos to recipients. Table


2016 ◽  
Vol 28 (2) ◽  
pp. 212
Author(s):  
M. Takayama ◽  
O. Dochi ◽  
K. Imai

In recent years, the use of ovum pick up (OPU) and IVF for embryo production has increased worldwide; however, the conception rate of embryo transfer is lower for OPU-IVF embryos than for in vivo-derived embryos. This study aimed to determine the efficacy of embryo selection by a 3-step observation method by using a micro-well culture dish (Dai Nippon Printing, Tokyo, Japan). In this study, 9 Holstein and 15 Japanese Black cows were used, and the OPU-IVF was conducted from October 2014 to May 2015. The collected cumulus-oocyte complexes (COC) were cultured for 22 h in 25 mM HEPES-buffered TCM-199 supplemented with 5% calf serum (CS) and 0.02 AU mL–1 of FSH. Sperm (at a final concentration of 5 × 106 spermatozoa mL–1) were incubated with COC for 6 h. After insemination, presumptive zygotes were separated from cumulus cells and sperm by pipetting. Then, the presumptive zygotes were cultured for 9 days in CR1aa supplemented with 5% CS by using a micro-well culture dish. Kinetics and morphology were observed at 27, 31, and 55 h post-insemination (hpi). The presumptive zygotes were divided to 3 groups (more than 2 cells, 2 cells, and no cleavage) at 27 and 31 hpi. Then, embryos at the 2-cell stage at 31 hpi were divided into 2 groups: 2-cell with normal cleavage and 2-cell embryos with abnormal cleavage (unequal cleavage, 2-cell with fragments, and 2-cell with protrusion). Subsequently, embryos were classified as 8-cell and more than 8 cell, or less than 8 cell at 55 hpi. The blastocyst rate (BL%) was analysed at 7, 8, and 9 days post IVF. Embryos selected by the 3-step observation method were used for fresh embryo transfer. The data were analysed by chi-squared test. In total, 856 oocytes were collected by OPU and 633 oocytes were cultured, of which 39.7% (263/663) developed to the blastocyst stage. The BL% of 2-cell embryos (72.5%, 116/160) was significantly higher (P < 0.01) than that of no cleavage (47.0%, 117/249) at 27 hpi. The BL% of 2-cell (65.4%, 206/315) and more than 2-cell (53.0%, 35/66) was significantly higher (P < 0.01 and P < 0.05) than that of embryos divided as no cleavage (25.9%, 22/85) at 31 hpi. The BL% was not significantly different between 2-cell with normal cleavage (68.5%, 172/251) and abnormal cleavage (53.1%, 34/64). The BL% of 8-cell and more than 8-cell stage (72.8%, 182/250) was significantly higher (P < 0.01) than that of embryos with less than 8 cells (38.8%, 81/209) at 55 hpi. Overall, 2-cell embryos at 27 hpi, 2-cell embryos with normal cleavage at 31 hpi, and 8-cell and more than 8 cell at 55 hpi showed the highest BL% (82.1%, 78/91). The conception rate was higher for following the selected fresh embryo transfer that was 70.6% (12/17) than average of in vitro fertilization embryos transfer that was 40.0%. These results demonstrate that the 3-step observation method used in this study can be effectively applied for the selection of IVF embryos that have a strong ability to develop into blastocysts and high competence for conception.


2008 ◽  
Vol 56 (2) ◽  
pp. 245-253 ◽  
Author(s):  
Chang-Liang Yan ◽  
Qi-En Yang ◽  
Guang-Bin Zhou ◽  
Yun-Peng Hou ◽  
Xue-Ming Zhao ◽  
...  

The present study was designed to investigate the cryotolerance of in vitro fertilised (IVF) mouse embryos at various preimplantation developmental stages. IVF mouse embryos were vitrified by the open-pulled straw (OPS) method. After warming, embryos were morphologically evaluated and assessed by their development to blastocysts, hatched blastocysts or term. The results showed that a high proportion (93.3–100.0%) of vitrified embryos at all developmental stages were morphologically normal after recovery. The developmental rate of vitrified 1-cell embryos to blastocyst (40.0%) or hatched blastocyst (32.7%) or term (9.3%) was significantly lower than that from other stages (P < 0.05). Vitrified embryos from 2-cell to early blastocyst stage showed similar blastocyst (71.8–89.5%) and hatched blastocyst rates (61.1–69.6%) and could develop to term without a significant loss of survival compared with those of fresh embryos (P > 0.05). Vitrified 2-cell embryos showed the highest survival rate in vivo (50.6%, 88/174), compared with that from other stages (9.3–30.5%, P < 0.05). The data demonstrate that the OPS method is suitable for the cryopreservation of IVF mouse embryos from 2-cell stage to early blastocyst stage without a significant loss of survival. Embryos at the 2-cell stage had the best tolerance for cryopreservation in the present study.


2005 ◽  
Vol 17 (2) ◽  
pp. 231
Author(s):  
V. Havlicek ◽  
F. Wetscher ◽  
T. Huber ◽  
M. Gilles ◽  
D. Tesfaye ◽  
...  

Oviduct as well as oocyte and embryo development are subject to developmental changes which have crucial effects on the application of in vivo culture. The present study aimed at optimizing in vivo culture of IVP bovine embryos at different developmental stages in the bovine oviduct. Cumulus oocyte complexes (COC) were collected from slaughterhouse ovaries, matured in vitro for 22 h and assigned to four groups. In groups I and II, oocytes were pre-incubated for 3 to 4 h with 5 × 106 sperm/mL, and then immediately transferred to recipients, which had just completed ovulation (group I), or kept in vitro for a further 12 to 18 h and transferred to Day 1 synchronized recipients (group II). In groups III and IV, COC were subjected to standard IVF/IVC; then embryos were either transferred at the 4- to 8-cell stage on Day 3 into the oviducts of Day 3-synchronized recipients (group III) or kept in vitro for a further 4 to 5 days (group IV). Thirty-four 18- to 30-month-old temporary recipients were synchronized using a standard Ovsynch protocol. COC and embryos were transferred and re-collected by transvaginal endoscopy. COC or embryos were loaded into a 180° curved glass capillary, which was inserted via the infundibulum 5 to 8 cm deep into the ampulla ipsilateral to the CL. On recipient Day 7, a 90° curved metal canula served for tubal flushing prior to conventional uterine embryo flushing. Sixty mL of PBS containing 1% fetal calf serum were rinsed through the oviduct into the uterus and a further 400 mL of medium were finally used for flushing of the uterine horn and collected via an embryo filter. Embryo development was evaluated directly after flushing (Day 7) and on Day 8. For statistical analysis (ANOVA), the blastocyst rates (Days 7 and 8) in group III were related to COC corrected by the collection rate. In group I, 575 COC were transferred to 11 recipients and 420 (73%) were re-collected as oocytes or embryos. The blastocyst yields on Day 7 and Day 8 were 23% (97) and 25% (104), respectively. In group II, the transfer of 489 presumptive zygotes into 13 heifers resulted in only 175 re-collected (36%), of which 15% developed into blastocysts (Day 7: 26; Day 8: 27). Ten heifers (group III) served for in vivo culture of 643 embryos at the 4- to 8-cell stage. On Day 7, 568 (88%) embryos were flushed and 171 (30%) reached the blastocyst stage. A further 24 h culture in vitro finally resulted in 244 (42%) blastocysts. The complete in vitro production system delivered 13% (63/477) blastocysts on Day 7 and 34% (161/477) blastocysts on Day 8. The collection rates (P < 0.001) and the blastocyst rates on Day 7 (P < 0.05) and Day 8 (P < 0.001) differed significantly in all groups. The present data demonstrate that the developmental stage of transferred complexes has an influence on embryo recovery as well as an embryo development. This work was supported by Austrian BMBWK and BMLFUW (#1227).


2007 ◽  
Vol 19 (1) ◽  
pp. 246
Author(s):  
A. Baji Gal ◽  
S. Mamo ◽  
S. Bodo ◽  
A. Dinnyes

Real-time PCR has the potential to accurately quantify the mRNA level of selected genes in single cells and individual pre-implantation-stage embryos. The goal of our study was to examine the variations in gene expression within individual embryos of the same stage and between embryos of the same stage but from different sources. In our study, we determined expression level of the 7 most commonly used housekeeping genes in 8-cell-stage mouse embryos produced under different culture conditions. Messenger RNA of 6 embryos each that was derived in vivo, or cultured in vitro from the zygote stage, or derived from oocytes activated parthenogenetically and developed in vitro were extracted individually followed by reverse transcription into cDNA. Optimized real-time PCR was performed for cytoplasmic beta-actin (Actb), glyceraldehyde-3-phosphate dehydrogenase (Gapdh), H2A histone family, member Z (H2afz), hypoxanthine guanine phosphoribosyl transferase 1 (Hprt1), ubiquitin C (Ubc), peptidylprolyl isomerase A (cyclophilin A) (Ppia), and eukaryotic translation elongation factor 1 epsilon 1 (Eef1e1) genes. The results were analyzed, and the percentage standard error of the mean relative expression value was compared for all genes. All 7 genes were presented above the detection limit in all samples. One or two individual embryos showed 2- to 4-fold higher mRNA levels than the average for all genes in the group. The embryos cultured in vitro showed much higher expression levels of H2afz, Ppia, and Eef1e1 genes than those in the in vivo group. The parthenogenetic group was similar to the in vivo group in expression of Actb, H2afz, Hprt, and Eef1e1 genes, but showed significant differences (P &lt; 0.05; Student's t-test) compared to the in vitro group (Table 1). The percent standard error of the mean decreased gradually as the number of samples was increased. The 6 individual embryos in similar groups showed relatively low variability compared to embryos at similar stage but produced in different conditions. Interestingly, the parthenogenetic embryos showed a level of gene expression comparable to that of the in vivo ones, notwithstanding their culture in vitro. In conclusion, morphological observations and similarity in developmental stage alone cannot guarantee the uniformity of embryo samples, and a minimum of 4–6 replicates per treatment is needed. Moreover, we showed that culture condition itself has an effect on housekeeping gene expression, which, if neglected, might result in misinterpretation of data. Table 1.Relative expression values of the different culture groups (mean ±SE; n =6 embryos) This work was supported by EU FP6 (MEXT-CT-2003-509582 and 518240), Wellcome Trust (Grant No. 070246), and Hungarian National Science Fund (OTKA) (Grant No. T046171).


Development ◽  
1981 ◽  
Vol 66 (1) ◽  
pp. 109-116
Author(s):  
T. W. Sadler ◽  
D. A. T. New

A comparison between static versus rotator culture systems and a variety of media (rat serum, new born calf serum, DMEM and Waymouth's) was made in an attempt to promote in vitro growth of mouse embryos from the beginning of neurulation (headfold stage) to the closure of the neural tube and formation of the limb buds (48 h). The results demonstrate that good development can be achieved for 48 h using a rotator system and that 80% of embryos cultured on rotators show growth and differentiation similar to that obtained for the same time period in vivo. Static cultures are less successful and embryos grown in this system show lower protein content and somite numbers than those maintained on rotators. Undiluted rat serum is superior to all other media tested and supports better growth and development as monitored by total protein and developmental abnormalities.


2014 ◽  
Vol 26 (1) ◽  
pp. 206 ◽  
Author(s):  
S. Chastant-Maillard ◽  
K. Reynaud ◽  
S. Thoumire ◽  
M. Chebrout

In vitro fertilization encounters 2 specific difficulties in the canine species, with no puppies born to date: low penetration rates (10–50%) and high polyspermia (around 50% of fertilized oocytes; Saint-Dizier et al. 2001 J. Reprod. Fert. Suppl. 57, 147–150). The objectives of the study were to test whether intracytoplasmic sperm injection (ICSI), which overcomes these 2 obstacles, could allow production of canine embryos, using in vivo- or in vitro-matured oocytes. The time of ovulation was determined on 8 Beagle bitches from our experimental kennel by blood progesterone assay and transabdominal ultrasound examination. After ovariohysterectomy 82 to 100 h after ovulation, 58 metaphase II (MII) oocytes were collected by tubal flushing. In parallel, 88 oocytes from 6 anoestrus bitches were matured in vitro (M199 + 20% fetal calf serum for 72 h in 5% CO2 at 38°C). Sperm was collected from 1 Beagle dog with excellent fertility record at natural mating. The sperm was diluted 1 : 100 in PBS/BSA without any selection process. Intracytoplasmic sperm injection was performed at 38°C in M199 HEPES + 20% BSA (4-μm injection pipette; 120-μm holding pipette). One motile spermatozoon of normal morphology was injected per oocyte. Injected oocytes were cultured in vitro for 48 h after injection (M199 + 20% fetal calf serum in 5% CO2 at 38°C) in 4-well open dishes. Oocytes were then fixed and DNA and tubulin were stained for observation by confocal microscopy (Chebrout et al. 2012 Microsc. Microanal. 18, 483–492). Among the 58 MII oocytes recovered in vivo, 7.4% lysed at injection and 20% degenerated during the 48 h after injection. Among the 40 injected oocytes still alive, 6 fragmented (15%) and 4 developed as embryos [10%; 2-pronuclei (n = 2), 2-cell and 6-cell). None of the other oocytes showed decondensed female chromatin. Among the 88 oocytes incubated for in vitro maturation, 13 (14.8%) reached MII. These were successfully injected; 48 h after injection, 3 were embryos at the 2-cell stage and 10 were at the MII stage with a condensed sperm head. Fifty-one non-mature oocytes were injected; 31 were at the germinal vesicle (GV) stage and the stage of others was not determined. Of the GV oocytes, 71% degenerated during culture after injection. The 9 surviving oocytes were still at the GV stage with condensed sperm head 48 h after injection. In conclusion, canine embryos can be obtained through ICSI. Nevertheless, this procedure induced low activation rates. Development at later stages, especially after transfer into a recipient female, is to be evaluated, in particular for in vitro-produced MII oocytes, of lower cytoplasmic competence (Viaris et al. 2008 Reprod. Fert. Dev. 20, 626–639).


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