Blastocyst Day Research Articles

The Blastocyst Production Rate and Incidence of Chromosomal Abnormalities by Developmental Stage in In Vitro Produced Porcine Embryos

The present study was conducted to determine the relationship between embryonic development speed at different stages (the cleaved stage at 52 h and the blastocyst stage at 6 days post insemination) and incidences of chromosome abnormalities in in vitro produced porcine embryos. Porcine oocytes were collected from 3-6-mm ovarian follicles obtained at a slaughterhouse and matured in modified NCSU-37 medium for 44-46 h. Following in vitro fertilization with a final concentration of 1 x 10(5) sperm/ml for 3 h, all oocytes were cultured in vitro for 52 h. Day-2 (52 h after insemination) embryos were classified according to their cleaved stages into 2-cell, 3- to 4-cell, 5- to 8-cell, and >8-cell stages; these were cultured separately for additional 4 days (Day 6). The resultant Day-6 blastocysts were classified according to the morphological diameter into 3 grades: Grade A, expanded blastocysts; Grade B, expanding blastocysts; and Grade C, early blastocysts. They were then analyzed chromosomally. The 3- to 4-cell and 5- to 8-cell embryos had significantly high blastocyst development rates (46.1 and 36.9%, respectively), and these blastocysts contained significantly more cells (40.2 and 42.4 cells, respectively) than those derived from 2-cell embryos and >8-cell embryos (28.6 and 26.5 cells, respectively). The incidence of chromosomal abnormalities was significantly higher in the blastocysts derived from 2-cell and >8-cell stage embryos than in the blastocysts derived from the other stage embryos. Furthermore, the grade A blastocysts had the lowest incidence of chromosomal abnormalities (35.3%) and contained the most cells (48.7 cells). Porcine in vitro production (IVP) yielded a high blastocyst rate and an excellent embryo quality when 3- to 4-cell and 5- to 8-cell stage embryos were selected on Day 2 after insemination. The same criteria yielded a higher quality of expanded blastocysts based on the stage of embryo development and morphology.

Glutamine and hypotaurine improves intracellular oxidative status andin vitrodevelopment of porcine preimplantation embryos

We previously developed an in vitro-production system for porcine embryos and reported that the addition of glutamine (Gln) and hypotaurine (HT) during in vitro culture improved embryo development. This study examined the effects of Gln and HT on in vitro development, intracellular oxidative status and DNA damage of porcine preimplantation embryos. Porcine zygotes produced by in vitro maturation (IVM) and in vitro fertilization (IVF) were cultured until day 2 (day 0 = day of IVF) in porcine zygote medium (PZM) including 2 mM Gln and 5 mM HT, namely PZM-5. On day 2, the cleaved embryos were selected and cultured for 24 h in PZM-5 to which one of the following substances was added: (1) none (control); (2) Gln; (3) HT; or (4) Gln + HT. After 24 h of culture in each medium, the embryos were then returned to PZM-5 and cultured until day 5. Day-5 blastocyst yield was significantly higher in the Gln and Gln + HT groups (p < 0.05) than in the control and HT groups. In addition, Gln + HT significantly increased the total number of cells in blastocysts (p < 0.05) compared with the control. Although the number of cells and the intracellular GSH levels in day-3 cleaved embryos did not differ among treatments, addition of Gln, HT or Gln + HT significantly (p < 0.05) reduced the intracellular H2O2 content and the extent of DNA damage compared with the control. These results indicate that the presence of Gln and HT in PZM-5 from day 2 to day 3 promotes the development of porcine embryos by improvement of intracellular oxidative status.

127 DEVELOPMENT AND QUALITY OF BOVINE MORULAE CULTURED IN SERUM-FREE MEDIUM WITH RETINOIC RECEPTOR SPECIFIC AGONISTS

In the cell, all-trans retinoic acid (ATRA), a vitamin A metabolite, binds to retinoic acid-receptor (RAR), whereas the ATRA isomere 9-cis-retinoic acid (9-cis-RA) binds to both RAR and the retinoid X receptor (RXR). Synthetic compounds such as LG100268 (LG; Ligand Laboratories) are highly specific to bind RXR, which allows to differentially study the RAR and RXR pathways. In previous work morulae treated with LG for 48 h showed to improve blastocyst development and to activate pro-apoptotic genes (in press), whereas ATRA for 24 h increased cell numbers in the inner cell mass (ICM) and the trophectoderm (TE) (Rodr�guez et al. 2006 Hum. Reprod. 21, 2149–2157). However, LG and ATRA were never both compared for 24 in medium with BSA, which is thought to be more appropriate to produce embryos for cryopreservation than serum-containing medium. In this work we analyze development, quality, and viability of morulae cultured with RAR and RXR agonists. Cumulus–oocyte complexes from slaughterhouse ovaries were matured and fertilized in vitro. Presumptive zygotes were cultured in synthetic oviduct fluid (SOF) +3 gL–1 BSA. On day 6, morulae were treated for 24 h with ATRA 0.7 µm, LG 0.1 µm, or no additives. Blastocyst development was monitored up to day 8. Differential cell counts were made on hatched blastocysts on days 7 and 8. Apoptosis and necrosis (TUNEL + nuclear histology) were made on day 8 expanded and hatched blastocysts. Data were analyzed by GLM and Duncan's test, expressed as LSM � SE, and development rates were expressed as percentages of cultured morulae (replicates [R] = 14 for development; R = 9 for cell counts; R = 4 for apoptosis; n = 1647 morulae). ATRA yielded more blastocysts on day 8 than LG and controls (72.2 � 2.2 v. 60.0 � 2.3 and 65.6 � 2.4, respectively; P &lt; 0.02), and more expanded blastocysts than LG (48.6 � 2.3 v. 36.6 � 2.4; P &lt; 0.02), but no more than controls (43.5 � 2.5). Day-7 and day-8 hatched blastocysts cultured with ATRA showed more total cells than day-7 controls (163.5 � 8.0 and 161.5 � 5.4 v. 137.7 � 8.9, respectively; P &lt; 0.05). However, in the presence of ATRA, day-8 blastocysts showed a strong cell reduction in the inner cell mass (ICM), whereas their day-7 counterparts conserved ICM/total cells proportions comparable to day-7 controls (11.0 � 1.2 v. 19.7 � 1.7 and 20.6 � 1.9, respectively; P &lt; 0.03). The LG increased apoptotic index (AI) and necrotic index (NI) in the ICM (AI: 14.5 � 2.4 v. 6.4 � 1.5 and 6.4 � 1.4; NI: 5.0 � 1.2 v. 0.9 � 0.8 and 1.6 � 0.7; for LG, ATRA, and controls, respectively; P &lt; 0.02). Embryos produced with ATRA showed improved development and cell distribution without increasing apoptosis and necrosis. Vitrification of excellent day-7 and day-8 blastocysts is in course to evaluate cryosurvival and further embryo transfer to determine full developmental competence. Grant Support: MEC, project AGL2005-04479. M. Muñoz is sponsored by FICYT.

Quality analysis of buffalo blastocysts derived from oocytes vitrified before or after enucleation and reconstructed with somatic cell nuclei

We investigated the potential of vitrified-warmed buffalo oocytes to develop to blastocysts after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT). In vitro-matured oocytes before and after enucleation (M-II oocytes and enucleated oocytes, respectively) were put in 7.5% DMSO and 7.5% ethylene glycol (EG) for 4, 7 and 10 min, and then vitrified (Cryotop device) after 1-min equilibration in 15% DMSO, 15% EG and 0.5 M sucrose. Following 4-, 7- and 10-min exposure, proportions of the post-warm oocytes with a normal vitelline membrane were similar (66–71% in M-II oocytes and 69–71% in enucleated oocytes). However, 18–20% of the normal M-II oocytes had no detectable first polar body in their perivitelline space (no potential for subsequent enucleation). When the post-warm M-II oocytes were treated for PA by 7% ethanol, 10 μg/mL cycloheximide and 1.25 μg/mL cytochalasin-D, parthenogenetic development into Day-7 blastocysts occurred in 10–13% of cultured oocytes, lower ( P < 0.05) than fresh (control) oocytes (24%). In the absence of the cooling and warming, blastocyst rates in the 4-min exposure group (22%), but not in the 7-min and 10-min exposure groups (14–15%), were similar to that in the fresh group (23%). The total cell number (group average 117–132 cells) and the ICM ratio (22–24%) of the PA blastocysts derived from vitrified M-II oocytes were comparable with fresh oocytes (127 cells and 25%). After SCNT (with fibroblast cells and vitrified-warmed oocytes), blastocyst rates were similar for the three exposure periods for M-II oocytes (8–10%) and enucleated oocytes (7–9%), but were lower ( P < 0.05) than in the fresh group (15%). The total cell number of the SCNT blastocysts derived from vitrified M-II and enucleated oocytes (80–90 and 82–101 cells) was smaller ( P < 0.05) than from fresh oocytes (135 cells); the ICM ratio of blastocysts derived from the M-II and enucleated oocytes after vitrification in 7- or 10-min exposure groups (20–22%) was not different ( P > 0.05) from fresh control oocytes (24%) or those in 4-min exposure group (M-II 23%, enucleated 24%). Thus, SCNT of swamp buffalo oocytes following vitrification before or after enucleation resulted in blastocysts with a slightly decreased cell number.

Measures of Maternal-Fetal Interaction in Day-30 Bovine Pregnancies Derived from Nuclear Transfer

Embryonic mortality and abnormal placental morphology have been reported by most researchers studying nuclear transfer (NT), and it now is accepted that placental anomalies and poor development of cloned embryos are related. As early as day 50 of gestation, cloned bovine concepti exhibit poor structural organization of the developing placentomes. These experiments were designed to identify alterations in maternal-fetal interactions during establishment of the placentas of NT-derived embryos at day 30 of gestation. Bovine NT embryos were produced using cultured fibroblast cells from a single Hereford donor cow, and control embryos were derived from in vitro fertilization (IVF). Following in vivo culture in ligated sheep oviducts, day-8 blastocysts were transferred to synchronized recipient heifers. Tissues recovered from viable day-30 pregnancies were analyzed by real-time RT-PCR, immunohistochemistry, and quantitative histological techniques. Immunoperoxidase staining of caruncular tissue from NT- and IVF-derived pregnancies revealed no significant differences in expression of the extracellular matrix proteins, collagen type IV and laminin, or the receptor subunits, integrins alpha1 and alpha3, suggesting that altered expression of these proteins at day 30 of gestation is not a primary cause of abnormal placentome structure in cloned concepti. Percentage of binucleate cells (BNC) within the trophoblast also was similar in NT- and IVF-derived pregnancies; however, expression of the BNC-specific placental lactogen (PL) transcript was elevated in NT-derived concepti (p < 0.05). These results indicate that regulation of PL transcription was altered in cloned day-30 placental tissues, suggesting the presence of irregular fetal-maternal signaling patterns that might undermine continued development of NT-derived concepti.

Pregnancies and live births after trophectoderm biopsy and preimplantation genetic testing of human blastocysts

To compare multiple-cell trophectoderm biopsy for preimplantation genetic diagnosis (PGD) from day-5 blastocysts with previously published experience with day-3 cleavage-stage embryos. Retrospective review of laboratory and clinical experience. Sydney IVF, a private clinic in Australia. Preimplantation genetic diagnosis (PGD) patients age < 44 years with at least one IVF blastocyst suitable for biopsy, recruited from January 2002 through August 2004. Biopsy of trophectoderm from blastocysts on day 5 or 6, with same-day PGD for mutation testing, translocation testing, aneuploidy screening or sex selection. Spare, normal biopsied blastocysts were cryostored for possible later transfer. Fetal heart-positive pregnancy rate and accumulating live birth rate after adding results from biopsied fresh and frozen blastocysts for particular couples. In 231 started PGD treatment cycles, unambiguous results were obtained from 974 of 1,050 biopsied blastocysts (93%); all blastocysts survived the biopsy procedure by reconstitution of their blastocele. One hundred nineteen women (median age, 36 years) have had 127 blastocysts transferred fresh (fetal heart-positive implantation rate, 41%). Of 146 blastocysts cryostored, 27 have been thawed (all with > 50% cell survival) and 24 transferred (implantation rate, 26%). To date, 53 pregnancies have been delivered or are ongoing, with an additional 4 clinical miscarriages (7%) and 6 subclinical miscarriages (total miscarriage rate, including biochemical pregnancies, 16%). There were no twin pregnancies. With technically appropriate blastocyst culture and freezing, blastocyst biopsy and cryostorage and later transfer of biopsied blastocysts is shown to be a practical and probably preferable path to preimplantation genetic testing of embryos compared with cleavage-stage embryo biopsy, being accompanied by a high implantation rate (and hence more conducive to elective single embryo transfer) and by a low rate of twinning and miscarriage.

Fluorescence in situ hybridization reanalysis of day-6 human blastocysts diagnosed with aneuploidy on day 3

To determine the concordance of day-6 blastocyst analysis with the day-3 fluorescence in situ hybridization (FISH) aneuploidy diagnosis. Retrospective study. In vitro fertilization laboratory. Six hundred sixty embryos were included from 94 IVF/intracytoplasmic sperm injection patients undergoing preimplantation genetic diagnosis. None. Single blastomeres biopsied on day 3. Aneuploidy screening for chromosomes 13, 18, 21, X, and Y were analyzed. Left-over blastocysts were reanalyzed on day 6. Among the 660 embryos evaluated, 367 (55.6%) were euploid and 281 (42.6%) were aneuploid. Of the euploid embryos, 213 embryos were transferred, 68 were frozen on day 5, and 86 were left. All 281 aneuploid embryos were further cultured, and 55 (19.6%) progressed to blastocysts. When FISH reanalysis was performed, 33 of 55 blastocysts (60%) were confirmed aneuploid in concordance with the day-3 diagnosis. However, 22 of 55 blastocysts (40%) were determined to be euploid. In addition, 207 aneuploid embryos (73.7%) arrested before day 6, as opposed to 32 of the 86 euploid embryos (37.2%). Day-3 single-cell embryo biopsy reveals that aneuploidy can be confirmed in 60.7% of the blastocysts on reanalysis. The majority of discordance is most likely due to embryo mosaicism and possibly a limited ability to "self-correct."

Gel-Loading Tip Vitrification of In Vitro-Matured Bovine Oocytes and Subsequent Embryo Production by IVF and Nuclear Transfer

The purpose of this study was to cryopreserve bovine oocytes for subsequent blastocyst production by in vitro fertilization (IVF) and somatic cell nuclear transfer (SCNT). A vitrification procedure using gel-loading tips as containers was applied to cryopreserve in vitro-matured and denuded oocytes. In Experiment 1, oocytes were vitrified-warmed in vitrification solution (VS) containing 25, 28, 31, or 40% ethylene glycol (EG) and 1.0 M sucrose. The proportions of survived oocytes that appeared to be morphologically normal after warming, and cleaved oocytes after IVF were lower with 25% EG-based VS when compared with 28–40% EG-based VS. Blastocyst yields 8 days after IVF of oocytes vitrified-warmed in 28 and 31% EG-based VS (12 and 17%, respectively) were not significantly different from those of the fresh control group (32%). Day-7 blastocysts derived from vitrified oocytes were composed of a smaller number of inner cell mass (ICM) and trophectoderm cells than the fresh Day-7 blastocysts. In Experiment 2, oocytes vitrified-warmed in 31% EG-based VS were subjected to enucleation and SCNT. The proportions of oocytes fused and cleaved in the vitrified group were comparable to those in the fresh control group. Blastocyst yields 6 and 7 days after SCNT of vitrified oocytes were lower than those of control oocytes, but 8 days after the SCNT, the difference became statistically comparable (45 versus 58% in control group). ICM and trophectoderm cell numbers in Day-7 blastocysts derived from vitrified oocytes were smaller than those of control blastocysts due to a slower developmental rate. In conclusion, bovine oocytes cryopreserved by vitrification in gel-loading tip were capable of developing into blastocysts after conventional IVF and SCNT, with slightly smaller cell numbers and a slower developmental rate.

Gene expression and developmental competence of bovine embryos produced in vitro under varying embryo density conditions

The objective of this study was to determine the effects of oocyte/embryo density (embryo number:medium volume ratio) on developmental competence and relative transcription of developmentally important genes in in vitro-produced bovine embryos. Using standard procedures, bovine oocytes were matured, fertilized and cultured in vitro in groups of 5, 10, 20 or 30 oocytes/embryos per 100 μL medium drop (embryo number/medium volume ratios of 1:20, 1:10, 1:5 and 1:3.3, respectively). A semi-quantitative RT-PCR assay was used to determine the relative abundance of Hsp 70.1 and Glut-1 transcripts in Day-6 morulae, and in Day-7 and Day-8 blastocysts and expanded blastocysts. Cleavage rates (55.9, 49.1, 47.1 and 34.6%, respectively) and blastocyst developmental rates (24.1, 18.9, 20.4 and 12.6%, respectively) were higher in groups containing 5, 10 and 20 embryos versus 30 embryos per drop, but there were no significant differences among groups in hatching rates. The relative abundance of Hsp 70.1 transcripts in Day-7 blastocysts was higher in embryos produced in the 20-embryo than in the 5-embryo groups. There were no differences among embryos from all groups in the amount of Glut-1 mRNA (regardless of embryonic stage). However, there were differences in the pattern of Hsp 70.1 gene expression between distinct stages of embryo development and embryo density; these dissimilarities appeared to be associated with compromised development at higher embryo densities. In conclusion, the increase in embryo density during IVM, IVF, and IVC phases of in vitro embryo production might negatively affect embryo development and the pattern of gene expression of in vitro-produced bovine embryos.

Efficiency of gene transfection into donor cells for nuclear transfer of bovine embryos

The production of transgenic (TG) animals by somatic cell nuclear transfer (SCNT) has proven to be a more efficient method than other methods, such as gene injection or sperm mediation. The present study was intended to evaluate the efficiency of gene transfection by Effectene (Qiagen, Inc.), a lipid-based reagent compared to electroporation in fetal-derived fibroblast cells (FFC), cumulus-derived fibroblast cells (CFC), and adult ear skin-derived fibroblast cells (AEFC). Parameters compared were factors such as chromosome abnormality, gene expression, and the incidence of apoptosis. Further, the TG embryos with transfected donor cells generated by electroporation or Effectene were compared to IVF and SCNT embryos in terms of rates of cleavage, blastocyst formation, and blastocyst cell number. Most of the cells (>80%) at confluence were at G0/G1 and considered to be suitable nuclear donors for cloning. Transfection with a plasmid containing the enhanced green fluorescent protein (pEGFP-N1) gene into FFC did not increase the incidence of chromosomal abnormalities. The rates of apoptosis in different cell types transfected with pEGFP-N1 were 3.3%-5.0%, and the values did not differ among groups. In addition, the rates of apoptosis in various cells between 5-7 and 20-22 cell passages did not differ. However, the efficiency of gene transfecton into FFC by Effectene reagent (14.2 +/- 1.7) was significantly (P < 0.05) higher than that obtained by electroporation (5.1 +/- 1.0). Among various cell types, the efficiency of gene transfection by Effectene and eletroporation of FFC (14.2 +/- 1.7 and 5.1 +/- 1.0, respectively) was significantly (P < 0.05) higher than transfection of CFC and AEFC by either method (9.4 +/- 1.5 and 3.3 +/- 0.8, 8.8 +/- 0.7, and 2.1 +/- 0.4, respectively). In TG embryos produced by SCNT with electroporation and Effectene, the rates of cleavage and blastocyst formation were significantly lower (P < 0.05) than those of IVF controls, but rates did not differ between SCNT and TG embryos. Similarly, significantly higher (P < 0.05) total cell numbers in day-8 blastocysts were observed in IVF controls than those in SCNT and TG embryos, but did not differ between SCNT and TG (136 vs. approximately 110, respectively). The results demonstrated that, though there were no difference in the rates of chromosomal aneuploidy and the incidence of apoptosis among various cell types, transfected with or without pEGFP-N1, FFC were the cell type most effectively transfected and Effectene was a suitable agent for transfection.

Derivation of human embryonic stem cells from day-8 blastocysts recovered after three-step in vitro culture.

Human embryonic stem cells (hESCs) have been derived from the inner cell mass (ICM) of day 5-7 blastocysts and hold great promise for research into human developmental biology and the development of cell therapies for the treatment of human diseases. We report here that our novel three-step culture conditions successfully support the development of day-8 human blastocysts, which possess significantly (p <.01) more ICM cells than day-6 blastocysts. Plating of ICMs isolated from day-8 blastocysts resulted in the formation of a colony with hESC morphology from which a new hESC line (hES-NCL1) was derived. Our stem cell line is characterized by the expression of specific cell surface and gene markers: GTCM-2, TG343, TRA1-60, SSEA-4, alkaline phosphatase, OCT-4, NANOG, and REX-1. Cytogenetic analysis of the hESCs revealed that hES-NCL1 line has a normal female (46, XX) karyotype. The pluripotency of the cell line was confirmed by the formation of teratomas after injection into severely combined immunodeficient mice and spontaneous differentiation under in vitro conditions.

Comparison on in vitro fertilized bovine embryos cultured in KSOM or SOF and cryopreserved by slow freezing or vitrification

The objectives of this study were to identify an improved in vitro cell-free embryo culture system and to compare post-warming development of in vitro produced (IVP) bovine embryos following vitrification versus slow freezing. In Experiment 1, non-selected presumptive zygotes were randomly allocated to four medium treatments without co-culture: (1) SOF+5% FCS for 9 days; (2) KSOM+0.1% BSA for 4 days and then KSOM+1% BSA to Day 9; (3) SOF+5% FCS for 4 days and then KSOM+1% BSA to Day 9; and (4) KSOM+0.1% BSA for 4 days and then SOF+5% FCS to Day 9. Treatment 4 (sequential KSOM–SOF culture system) improved (P>0.05) morulae (47%), early blastocysts (26%), Day-7 blastocysts (36%), cell numbers, as well as total hatching rate (79%) compared to KSOM alone (Treatment 2). Embryos cultured in KSOM+BSA alone developed slowly and most of them hatched late on Day 9, compared to other treatments. In Experiment 2, the sequential KSOM–SOF culture system was used and Day-7 blastocysts were subjected to following cryopreservation comparison: (1) vitrification (VS3a, 6.5M glycerol); or (2) slow freezing (1.36M glycerol). Warmed embryos were cultured in SOF with 7.5% FCS. Higher embryo development and hatching rates (P<0.05) were obtained by vitrification at 6h (71%), 24h (64%), and 48h (60%) post-warming compared to slow freezing (48, 40, and 31%, respectively). Following transfer of vitrified embryos to synchronized recipients, a 30% pregnancy rate was obtained. In conclusion, replacing KSOM with SOF after 4 days of culture produced better quality blastocysts. Vitrification using VS3a may be used more effectively to cryopreserve in vitro produced embryos than the conventional slow freezing method.

280LAMBS BORN AFTER IN VITRO EMBRYO PRODUCTION FROM PREPUBERTAL LAMB OOCYTES AND FROZEN-THAWED UNSORTED AND SEX-SORTED SPERMATOZOA

Developments in sperm sexing technology have resulted in the birth of a number of offspring after IVF of oocytes from adult animals (Johnson LA, 2000 An. Reprod. Sci. 60–61, 93–107). The aim of this study was to combine sperm sexing technology with juvenile breeding. Merino lambs, 2–3 weeks (n=43) were hormone stimulated (Morton KM et al., 2003 Proc. Soc. Reprod. Fert., P18), and COCs were matured in TCM-199 (Sigma) with 10μgmL−1 p-FSH (Folltropin-V; Bioniche Animal Health Australasia), 10μgmL−1 pLH (Bioniche), and 20% sheep serum (v/v) in a humidified 6% CO2, 5% O2, 89% N2 atmosphere for 22h. Semen collected from Merino rams was diluted and frozen as pellets (Unsorted), or stained with H33342, separated into X and Y sperm using a SX MoFlo (Cytomation Inc., Fort Collins, CO, USA), and frozen as pellets (Sorted). Sperm were prepared for IVF by swim-up under 0.5mL of SOF with 2% sheep serum (v/v; SOF+) for 45min (Unsorted), or diluted in 0.5mL of Sydney IVF Sperm Buffer (Cook IVF, Brisbane, Australia) and centrifuged at 650g for 3min (Sorted). After IVM, oocytes were transferred to SOF+, and cultured with 0.5×106mL−1 (Unsorted) or 1.0×106mL−1 (Sorted) motile sperm for 18h. Presumptive zygotes were transferred to Sydney IVF cleavage and blastocyst medium (Cook IVF) for 3 and 5 days, respectively. Oocyte maturation and fertilization were assessed by orcein staining 18h post-insemination (hpi). Two Day-7 blastocysts were transferred to each recipient ewe (n=9; 3 per group) and pregnancies diagnosed by ultrasound on Day 57 of gestation. Data were analyzed by chi-square test. Oocyte maturation was 83.9% (73/87), and monospermic fertilization did not differ for Unsorted (22/32; 68.7%), X- (6/14; 42.8%), and Y-sperm groups (15/27; 55.6%). Polyspermic fertilization was 9.4% (3/32) and 7.4% (2/27) for the Unsorted and Y groups. Cleavage was reduced with X- and Y-sperm compared with Unsorted, but blastocyst formation (from cleaved oocytes) did not differ (Table 1). There were three (100%), zero (0%), and one (33.3%) pregnancies from Unsorted, X- and Y-embryos, respectively, all of which survived to birth, demonstrating that juvenile breeding can be successfully combined with sperm sexing. Table 1 Cleavage and blastocyst formation after IVF with Unsorted, X- or Y-sperm. Values in parenthesis are percentages

285BIRTH OF PIGLETS AFTER NON-SURGICAL TRANSFER OF PORCINE EMBRYOS CULTURED IN PZM-4 WITH ALTERED CONCENTRATIONS OF AMINO ACIDS

We previously developed an in vitro production (IVP) system for porcine embryos and obtained piglets after surgical transfer of blastocysts cultured in Porcine Zygote Medium (PZM)-4. However, the developmental competence of pig IVP embryos to the blastocyst stage is still low and further improvement of IVC medium is needed. In the present study, we evaluated the effects of the addition of glutamine (Gln), hypotaurine (HT), taurine (Tau), BME-essential (EA) and MEM-nonessential (NA) amino acids solutions to PZM-4, and the replacement of polyvinyl alcohol (PVA) with BSA on embryo development to blastocysts. Moreover, the developmental competence of IVP blastocysts after nonsurgical embryo transfer (NS-ET), using a flexible catheter (FC) for deep intrauterine insemination, was investigated. Porcine COC from prepubertal gilts were matured and fertilized in vitro, using frozen-thawed ejaculated boar semen. Presumptive zygotes were cultured in PZM-4, as a basal culture medium, until Day 5 after IVF. Data from six replicates were analyzed by ANOVA. Addition of 0.25 to 4mM Gln to PZM-4 (containing 5mM HT) significantly increased the percentage of embryos that developed to blastocysts (15 to 31%), with addition of 2mM Gln significantly increasing the total cell numbers in blastocysts (43±17 cells) compared with no addition (3% and 20±4 cells, respectively). Addition of 1.25 to 10mM HT to HT-free PZM-4 supplemented with 2mM Gln (named PZM-5) significantly increased the percentage of embryos that developed to blastocysts (22 to 28%) compared with control (no HT;; 4%). In the culture with HT-free PZM-5, addition of 5mM Tau significantly increased blastocyst yield (17%) compared with control (4%). However, Tau addition in the presence of 5mM HT had no effect on development to the blastocyst stage. In combinations of EA and NA added to PZM-5, a single dose of EA significantly increased the percentage of embryos that developed to blastocysts (27%) compared with no dose (19%) or with a double dose of EA (20%), while a double dose of NA significantly increased the total cell numbers in blastocysts (43±16 cells) compared with no NA (37± 6 cells). Replacement of PVA with BSA in PZM-5 had no effect on embryo development to the blastocyst stage. Crossbred sows were used as recipients for NS-ET, and had their estrous cycle synchronized by a described previously method (Yoshioka et al., 2002 Biol. Reprod. 66, 112–119). Five days after hCG injection, a FC was introduced via the cervix into the uterine horn of recipients without sedation. Day-5 blastocysts cultured in PZM-5 were then transferred together with 5ml of TALP-Hepes (45 to 50 blastocysts/recipient). Of 6 recipients, one sow became pregnant and farrowed 7 piglets. Our results indicate that the addition of amino acids to PZM-4 can improve porcine embryo development to the blastocyst stage, and that blastocysts cultured in a chemically defined medium, PZM-5, can develop to full-term following NS-ET.

290EFFECTS OF HYALURONAN ON IN VITRO DEVELOPMENT OF PORCINE EMBRYOS CULTURED IN A CHEMICALLY DEFINED MEDIUM

Hyaluronan (HA), a glycosaminoglycan present in follicular and oviductal fluids, has been related to sperm capacitation, fertilization and embryo development. We have previously developed an in vitro-production (IVP) system of porcine embryos, where porcine blastocysts can be produced by IVF and IVC in chemically defined media and can develop to full-term by transfer to recipients. The application of a chemically defined medium to IVP in pigs allows the analysis of the physical action of substances on the development of pre-implantation embryos. In the present study, the effects of HA on the development of porcine embryos in a chemically defined medium were investigated. Porcine presumptive zygotes were produced by IVM and IVF of COC from pre-pubertal gilts and frozen-thawed ejaculated boar semen. The zygotes were cultured in Porcine Zygote Medium (PZM)-5 containing different concentrations of HA (0 [control], 1, 2, 5, 10, 20 and 50μgmL−1) until 6 days after IVF, and representative specimens were fixed for cell counting and transmission electron microscopy. Data of percentages and cell numbers were statistically analyzed by one-way ANOVA and Fisher’s PLSD test. The percentage of embryos that developed to the blastocyst stage (15.8% [23/144] to 19.5% [27/139]) did not differ among treatments. However, addition of 5 or 10μgmL−1 HA increased (P&amp;lt;0.05) the total number of cells in blastocysts (56.1 and 58.3 cells [n=22 and 23], respectively) compared to control (no HA, 42.0 cells [n=23]). To evaluate proliferation rates of inner cell mass (ICM) and trophectoderm (TE), embryos were cultured in PZM-5 for various periods of exposure to 10μgmL−1 HA. The numbers of ICM and TE cells in Day-6 blastocysts cultured in the presence of exogenous HA from Day 0 to Day 3 (18.3 and 34.4 cells, respectively [n=38]) or Day 6 (17.9 and 35.9 cells, respectively [n=36]) were significantly (P&amp;lt;0.05) higher than those cultured without HA through the culture period (13.5 and 24.2 cells, respectively [n=26]). In the presence of HA from Day 3 to 6, only the number of TE cells (37.1 cells [n=33]) increased (P&amp;lt;0.05), compared to PZM-5 alone. Differences in ultrastructure were noticed among blastocysts cultured with or without 10mgmL−1 HA. Blastocysts cultured with HA had mainly mature mitochondria while many mitochondria appeared morphologically immature in the blastocysts cultured without HA. Lipid droplets in the blastocysts cultured with HA seemed to be more homogeneous in comparison with those in the blastocysts cultured in PZM-5 alone. Further differences were seen in the numbers of lysosome-like structures, which were greater in blastocysts cultured with HA. This study demonstrates that exogenous HA improves cell proliferation and normality of ICM and TE in porcine embryos cultured in a chemically defined medium, depending on the exposure periods to HA. (Supported by MAFF, Japan and STINT, Sweden.)

Cryopreservation and sexing of in vivo- and in vitro-produced bovine embryos for their practical use.

My research awarded includes contributions to cryopreservation and sexing of bovine embryos produced in vitro and in vivo, as follows; (1) In vivo-derived morulae and blastocysts were cryopreserved in the presence of 10% glycerol, and the embryos were transferred into recipients after two-step dilution of glycerol in straw, with a practically acceptable pregnancy rate. (2) The survival rate of 16-cell stage embryos frozen in the medium with ethylene glycol was higher than that with DMSO or 1,2-propanediol. Addition of linoleic acid-albumin to culture medium enhanced the survival rate of post-thaw bovine 16-cell stage in vitro-produced (IVP) embryos. (3) Polarization of cytoplasmic lipid droplets by centrifugation of 2-cell stage embryos was found effective to increase freezing tolerance in 16-cell stage embryos developed from the centrifuged embryos, because blastomeres of 16-cell stage embryos were mostly lipid-free. (4) The usefulness of gel-loading tip (GL-Tip) as a container for ultra-rapid vitrification was demonstrated in IVP embryos from 2-cell to blastocyst stages, with a higher in vitro survival than the conventional two-step freezing. (5) PCR analysis for sexing of in vivo-derived Day-7 embryos indicated that male embryos developed faster and graded higher than female embryos. But such correlation between genetic sex and embryonic development was not found in IVP embryos obtained from individual cows. (6) Addition of 0.1-1.0% deproteinized hemodialysate product from calf blood to culture medium increased the producing efficiency of demi-embryos with good quality. Female embryos rather than male embryos required a longer time to repair after bisection. (7) In vivo-derived bovine embryos after biopsy for sexing by PCR analysis and subsequent vitrification using GL-Tips are available to practical use in the field. (8) Introduction of primer extension preamplification-PCR and purification of DNA product before standard sexing PCR of biopsy samples from Day 3-4 in vitro-derived embryos allowed accurate sex determination, and Day-7 blastocysts developed from Day 3-4 embryos were cryopreserved by GL-Tip vitrification without a loss of their viability. Thus the field application of bovine embryo transfer is in part supported by improvements of technologies in embryo cryopreservation and sex pre-determination.

Efficient production of sex-identified and cryosurvived bovine in-vitro produced blastocysts

To establish a protocol for production of bovine in-vitro produced (IVP) blastocysts that were sex-identified and cryopreserved, we examined the sexing efficiency and accuracy of Day-3 and Day-4 embryos by polymerase chain reaction (PCR), the development of the biopsied embryos into Day-7 blastocysts and the freezability of these blastocysts by vitrification in gel-loading tips. One or two blastomeres were isolated from IVP embryos at either the 8-cell or 16-cell stage (Days 3 and 4, respectively) by a pressing-out method, and were then subjected to primer extension preamplification (PEP)-PCR. The successful sex-identification rate of biopsied samples amplified, purified and analyzed for sex by a second PCR (88.9%) was higher than that of those amplified and analyzed without purification (32.0%). Developmental rates into Day-7 blastocysts of biopsied embryos (Day-3, 65.5%; Day-4, 70.8%) were similar to those of non-biopsied control embryos (Day-3, 74.5%; Day-4, 65.1%). Total cell numbers and the inner cell mass (ICM) ratio of blastocysts derived from biopsied embryos were also comparable with those of control embryos. Blastocysts were vitrified-warmed in the presence of 20% DMSO, 20% ethylene glycol and 0.6 M sucrose using gel-loading tips as containers. The proportions of biopsied blastocysts that were hatched or hatching rates after warming were high, regardless of the biopsy time (Day-3, 94.1%; Day-4, 91.9%), similar to the rates for control blastocysts (Day-3, 97.5%; Day-4, 96.9%). In conclusion, a protocol that allows sexing of Day-3 and Day-4 bovine embryos without compromising either the developmental ability to the blastocyst stage or freezability of Day-7 blastocysts was developed.

Chromosomal abnormalities in Day-6, in vitro-produced pig embryos

A cytogenetic study was undertaken to quantify, by chromosomal karyotyping, the incidence and type of chromosomal abnormalities present in Day-6 in vitro-produced (IVP) porcine embryos. Morphologically normal Day-6 blastocysts ( n=318) were fixed and grouped into six classes according to the number of total cells (from ≤20 to 61–70). Of 248 embryos suitable for analysis, 97 (39.1%) displayed chromosomal abnormalities. The abnormalities included haploidy (9.3%), polyploidy (71.1%) and mixoploidy (19.6%). Within polyploid embryos, triploidy and tetraploidy showed the highest incidence (56.5 and 27.5%, respectively); among mixoploid embryos, diploid-triploid embryos (2n/3n) were prevalent (36.8%). Overall, the mean cell number was 34.3±12.1 and the mitotic index was 8.6±6.1. Chromosomally abnormal embryos had fewer ( P<0.01) total cells compared to normal (2n) embryos (31.8±1.3 versus 35.9±1.0). In addition, the incidence of polyploidy decreased as the number of cells increased, while that of mixoploidy did not differ. These data indicate that polyploidy affects a large percentage of IVP porcine embryos capable of developing to blastocysts and the incidence of chromosomal abnormalities is much higher than that reported previously in in vivo embryos in this species. Given the ability of morphologically normal embryos with an abnormal chromosome complement to undergo preimplantation development in vitro, and the inability to identify blastocysts with abnormal karyotype without cytogenetic analysis, careful consideration should be given to factors affecting ploidy of IVP embryos, especially the incidence of polyspermic fertilization, when evaluating criteria of a porcine in vitro embryo production scheme.

Cryopreservation of Follicular Oocytes and Preimplantation Embryos in Cattle and Horses.

Factors affecting sensitivity of preimplantation embryos and follicular oocytes to cryopreservation were analyzed in the equine and bovine species. (1) Survival of equine blastocysts after two-step freezing in the presence of glycerol as the cryoprotective agent (CPA) was influenced by development of the embryonic capsule. The use of ethylene glycol (EG) with sucrose as CPAs improved the post-thaw survival of blastocysts and made it possible to transfer the embryos into recipient mares without removing the CPAs. In addition, early blastocysts cryopreserved by vitrification could develop both in vitro and in vivo when the embryos were exposed to vitrification solution in a stepwise manner. The vitrification procedure was also applied to the relatively large expanded blastocysts. (2) Bovine embryos produced in vitro have been considered to be highly sensitive to the process of cryopreservation. To solve this problem, Day-7 blastocysts produced in a serum-free system were cooled at 0.3 C/min rather than 0.6 C/min before being plunged into liquid nitrogen, resulting in no loss of the post-thaw viability. The supplementation of LAA in IVM/IVF media or IVC medium was effective in producing pronuclear-stage zygotes or morula-stage embryos relatively tolerable to freezing, respectively. (3) Transmission electron microscopic observation of immature equine oocytes showed that cellular injury occurred near the sites of gap-junctions between cumulus cells and the oocyte. In cattle, higher fertilization rates of oocytes were obtained when the oocytes were subjected to cryopreservation at an intermediate stage during IVM (GVBD for freezing, Met-I for vitrification). Vitrification of bovine Met-II oocytes in open-pulled glass capillaries, characterized by an ultra-rapid cooling rate (3,000-5,000 C/min), was found to avoid any harmful influence of vitrification and warming.

Clinical outcome after transfer of human blastocysts (BLs) vitrified on day 5 and on day 6 with a cryoloop technique

Objective: To optimize clinical outcomes of BL transfer, it is essential to establish a simple, fast and reliable procedure for the cryopreservation of BLs. We have reported the effectiveness of ultra-rapid vitrification using a cryoloop technique for human BLs (1). However, the timing of vitrification of BLs might affect the outcome. This study examined the post-warming survival and clinical outcome of human BLs vitrified on day 5 and on day 6. Design: Retrospective study on the vitrification human BLs. Materials/Methods: A total of 129 patients who had supernumerary BLs between Oct 1999 and Nov 2001 entered this study. A sequential culture system was used to obtain BLs. When embryos reached the BL stage 5 or 6 days after oocyte retrieval and patients agreed to cryopreserve the embryos by ultra-rapid vitrification, supernumerary BLs were cryopreserved using a cryoloop technique (1). Blastocysts were mounted on a minute nylon loop, which creates a thin, filmy layer of the solution by surface tension, and vitrified with the use of a two-step loading process with cryoprotectants at 37C. Initially, BLs were placed in cryoprotectant solution I, which is the base medium (Hepes-buffered modified HTF) containing 7.5% DMSO and 7.5% ethylene glycol (EG), for 2 min before being suspended in cryoprotectant solution II, which is the base medium containing 15% DMSO, 15% EG, 1% Ficoll 70 and 0.65 M sucrose, for 30 sec. Blastocysts were warmed and diluted in two steps with 0.33 M sucrose for 2 min and 0.2 M sucrose for 3 min. Blastocysts with morphologically intact inner cell mass and trophectoderm and a re-expanding blastocoel were judged to have survived and were transferred to the patient 5 days after progesterone administration, regardless of the timing of vitrification. Results: Of 301 day-5 BLs collected from 92 cycles, 274 (91%) survived after warming. Of 143 day-6 BLs collected from 45 cycles, however, only 77 (54%) survived (p <0.01). Pregnancy rates with day-5 and day-6 BLs were 39% (35/92) and 28% (10/45), respectively, and implantation rates with day-5 and day-6 BLs were 21% and 17%, respectively, both rates being not significantly different (p >0.05). Conclusions: Blastocysts on day 5 are more resistant to vitrification than those on day 6. Fast-developing embryos might be more viable than slow-developing ones. In addition, since more day-6 BLs had a larger blastocoel, BLs having a smaller blastocoelic cavity may be suitable for vitrification, probably with less risk of intracellular ice formation. However, once BLs survived vitrification, they seem to have similar ability to develop after transfer. Reference: (1) Mukaida T, Nakamura S, Tomiyama T, Wada S, Kasai M, Takahashi K (2001) Successful birth after transfer of vitrified human blastocysts using a cryoloop container-less technique. Fertil Steril 76: 618–620. Supported by: none.