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PubMed1982

The ability of fetal calf serum, new-born calf serum and normal steer serum to promote the in vitro development of bovine morulae.

The objective of this study was to compare fetal calf serum, new-born calf serum and normal steer serum as medium supplements in the development of bovine morulae in vitro . Bovine morulae were cultured in Hams F-10 tissue culture medium (HF-10) supplemented with 5% or 10% (v/v) fetal calf serum (FCS), new-born calf serum (NBCS) or normal steer serum (NSS). Embryos were recovered at slaughter from mixed bred donor cows of mixed breeding following estrus synchronization with prostaglandin and superovulation with follicle stimulating hormone. A total of 88 morulae were recovered, washed in HF-10 + 1% Bovine Serum Albumin and randomly assigned to treatments. Embryos were cultured in microdrops of medium under paraffin oil at 37 degrees C in a 5% CO(2) humidified atmosphere. Observations for stage of development were made every 24 hours. In vitro development was analyzed by assigning to each embryo a value of 0-5 based on the most advanced stage reached (0= no development, 5= development to a hatched blastocyst). Analysis of variance of these data revealed a significant treatment effect (P<.001) while no level effect or treatment x level interaction was apparent. Comparison of treatment means by Duncans new mulitple range test showed that NSS was superior to NBCS (P<.05) which was in turn superior to FCS (P<.05) as supplements of HF-10 in promoting the in vitro development of bovine morulae.

Journal Article↗
PubMed1994

Effect of human leukemia inhibitory factor on in vitro development of parthenogenetic bovine morulae.

The present study was conducted to investigate the effect of human leukemia inhibitory factor (hLIF) addition to synthetic oviduct fluid medium (SOFM) supplemented with human serum (HS) on the development of in vitro matured and parthenogenetically activated bovine oocytes. The oocytes matured for 30 h were exposured to ethanol (7%, 7 min) and cytochalasin B (5 mug/ml, 5 to 6 h). The treated oocytes were cultured for 5 d in SOFM supplemented with HS, and Day-5 morulae were cultured for 2 d in SOFM supplemented with HS and with or without hLIF (5000 U/ml) to investigate the subsequent in vitro development to the blastocyst stage. Of the 1531 oocytes that were parthenogenetically activated, 592 (37.5%) cleaved to the 2- to 8-cell stage and 174 (13.8%) developed to the morula stage. The addition of hLIF at the morula stage resulted in a significantly (P<0.01) higher rate of development to the blastocyst stage in the medium with hLIF (55.9%) than without hLIF (28.9%). The mean cell number per blastocyst developed in the medium with hLIF was also significantly (P<0.01) higher than that developed in the medium without hLIF. To evaluate the viability, 6 parthenogenetically developed blastocysts were transferred to 3 recipient heifers (2 embryos per heifer), while in 2 other recipient heifers estrus was prolonged after transfer. The plasma progesterone levels of the 2 recipient heifers at the 28th day after transfer were 8.1 ng/ml and 9.0 ng/ml, but pregnancy was not observed by ultrasonic scanning. The present results indicate that the addition of hLIF to in vitro-produced, Day-5 parthenogenetic bovine morulae significantly improves the subsequent development to the blastocysts stage; however, the present method still does not promote for development of parthenogenetic fetuses in cattle.

Journal Article↗
PubMed1997

Differential patterns of blastulation in bovine morulae cultured in synthetic oviduct fluid medium containing FCS or BSA.

This study examined the effects of fetal calf serum (FCS) supplementation of culture medium on blastulation and hatching of bovine morulae cultured in vitro. The presumptive zygotes derived from in vitro maturation and fertilization (IVM/IVF) were cultured in the modified synthetic oviduct fluid medium containing 3 mg/ml BSA (mSOF-BSA). At 120 h post insemination, morulae were randomly assigned to culture with mSOF-BSA (control) or mSOF containing 5% FCS (mSOF-FCS) instead of BSA. The replacement of BSA with FCS in mSOF significantly increased the percentage of blastocyst formation from Day 6 to Day 10 (Day 0 = the day of in vitro insemination) and the hatching rate of embryos on Days 8 and 9. The total number of cells in morulae and blastocysts on Day 6, in blastocysts on Day 7, and in blastocysts and hatched blastocysts on Day 8 were similar among the treatments. However, the replacement of BSA with FCS in mSOF significantly increased the total number of cells in hatched blastocysts on Day 10. Although the time of blastulation of embryos was significantly accelerated by the replacement of BSA with FCS in mSOF, the total number of cells in embryos at blastulation was lowered. The total number of cells in embryos at blastulation showed a time-dependent decrease when the embryos were cultured in mSOF-BSA. In contrast, the total number of cells in embryos that were cultured in mSOF-FCS depended little on the time after in vitro insemination. The results indicate that FCS supplementation of culture medium increased the percentage of embryos developing to the blastocyst stage without an increase in the total number of cells. However, an acceleration in the hatching rate and an increase in the total number of cells in hatched blastocysts were observed, compared with that in BSA-supplemented medium. It is suggested that FCS in the culture medium initiates earlier blastulation with fewer total numbers of cells in the morulae than BSA during in vitro culture of bovine embryos.

Journal Article↗
PubMed1997

Proteins of morula-like cells in hemolymph of the giant clam, Tridacna derasa.

The morula-like cell, a hemocyte packed with many large (about 3 microns in diameter) electron-dense granules, is found only in the hemolymph of giant clams belonging to the Tridacnidae. To clarify the function of the morula-like cell, we investigated its proteins, especially those found in the large granules. Proteins with molecular weights of 64 kDa, 17 kDa and 7.4 kDa were found to be specific to this type of hemocyte. N-terminal amino acid sequence analysis revealed that the 17-kDa and 7.4-kDa proteins were novel proteins rich in aromatic amino acids. Rabbit polyclonal antibody against a synthetic peptide of the 7.4-kDa protein reacted not only with that protein but also with a larger molecular weight (about 16-kDa) protein in the morula-like cell. Examination of the N-terminal amino acid sequences showed that the 16-kDa protein is distinct from the 17-kDa protein, and Western blot analysis suggested that it is a precursor of the 7.4-kDa protein. The zooxanthellate portion of clam mantle and kidney contained proteins immunoreactive to the antibody, but the azooxanthellate portion of the mantle did not contain any immunoreactive protein. These results suggest that the morula-like cells interact with the zooxanthellae.

Amino Acid Sequence↗
PubMed1993

Survival of mouse morulae and blastocysts derived from in vitro fertilization after ultra rapid freezing.

Mouse morulae and blastocysts derived from in vitro fertilization were placed in a highly concentrated vitrification solution (DAP 213:2 M dimethyl sulfoxide, 1 M acetamide, 3 M propylene glycol in PB 1) in a sampling tube at room temperature, plunged into liquid nitrogen within ten seconds and cryopreserved. Thawing was carried out by directly pouring 37 degrees C 0.3 M sucrose solution into the sampling tube. The ratios of morphologically normal embryos at the morula and blastocyst stages after thawing were 92.0% (149/162) and 13.3% (13/98), respectively. The rate of development from morphologically normal morulae into blastocysts in vitro was 83.1% (74/89). Some of the morphologically normal morulae were transferred to pseudopregnant recipients immediately after thawing, and 45.0% (27/60) of the embryos developed into normal young.

Animals↗
PubMed1983

Reassortment of cells according to position in mouse morulae.

Sixteen-cell mouse morulae were disaggregated and blastomeres originally occupying outer or inner positions were separated. Outer, inner, or unsorted populations of blastomeres were labeled with either trinitrobenzene sulphonic acid (TNP) or fluorescein isothiocyanate (FITC) and individual blastomeres aggregated to unlabelled partially decompact eight- to ten-cell morulae. After up to 6 h in culture, the positions of the labelled blastomeres within the aggregates were examined. The combined results demonstrated that between 86 and 92% of outer cells remained on the surface of the aggregate and flattened into extensive polygonal shapes, whereas 76-77% of the inner cells had become engulfed by the host morula cells and retained their initial spherical shape. Using unsorted cells, 33-37% were internalised, which is compatible with the most recent estimates of the presence of six to eight inner cells at the 16-cell stage. The possibility that differential adhesiveness of the outer and inner cells is involved in the allocation of cells to the trophectoderm and inner cell mass of the blastocyst is discussed.

Animals↗
PubMed1991

Cryopreservation of mouse half-morulae and chimeric embryos by vitrification.

Mouse half-morulae were cryopreserved less than or equal to 1, 3, 6, and 12 hr after bisection by the vitrification method using 25% glycerol and 25% 1,2-propanediol as cryoprotectant. The developmental rates of the frozen-thawed half-embryos to blastocysts in vitro were 77.8% (63/81), 82.0% (41/50), 92.1% (117/127), and 0% (0/37), respectively. Sixty-one of the half-embryos that had been vitrified 6 hr after the bisection followed by transfer to five recipients resulted in a total of ten (16.4%) normal fetuses. Chimeric mouse embryos constructed by two half-morulae were also vitrified 6 and 16 hr after aggregation. Survivors were obtained from the former case: 40 (80.0%) of 50 frozen-thawed embryos developed in vitro to blastocysts, and, after transfer, six chimeric offspring were obtained from the 34 vitrified chimeric embryos. These results showed that mouse half-morulae and chimeric embryos could be cryopreserved by the vitrification method. It seems possible to manufacture a chimeric mouse embryo of defined genotypic composition that can be analyzed during its frozen state using the identical half-embryos of the components.

Animals↗
PubMed1988

Production of chimeric rabbits from morulae by a simple procedure.

Experiments were conducted to develop a simple and reliable technique to produce chimeric rabbits from morula stage embryos. In Experiments 1 and 2, an in-vitro test of viability was initially performed by culturing embryos to the blastocyst stage. Ninety-three percent of the "chimeric" embryos developed to the blastocyst stage compared to 94% for controls when embryos were manipulated soon after collection (Exp. 1). Eight-one percent chimeric embryos and 78% control embryos developed to blastocyst stage when embryos were held at room temperature for 4 hr (Exp. 2). In Experiment 3, enough morula-stage embryos were available from true breeding Dutch-belted and albino rabbits to form potentially 67 diverse "color" pairs. These micromanipulated pairs of morulae were successfully combined to produce 64 chimeric embryos (96%, 64/67). They were transferred to the uteri of seven recipient does and three became pregnant producing 13 young. Four of the young exhibited substantial overt chimerism (31%) and one more was a possible chimera.

Animals↗
PubMed1998

Cellular composition and viability of demi- and quarter-embryos made from bisected bovine morulae and blastocysts produced in vitro.

The cellular composition and viability of intact, IVP embryos were compared with those of demi- and quarter-embryos produced by bisection of IVP morulae and blastocysts. Embryos were produced by established techniques from oocytes harvested from slaughterhouse ovaries. In Experiment 1, morulae at Day 6 or blastocysts at Day 7 were bisected on an inverted microscope using a microsurgical steel blade. Demi-embryos were then cultured without a zona pellucida until Day 8, when they were morphologically assessed for quality (viability). A higher proportion of demi-embryos made from blastocysts than from morulae were classified as viable (381/420, 91% vs 164/267, 61%; P < 0.001). In Experiment 2, only Day 7 blastocysts were bisected, and some of the resulting demi-embryos were bisected a second time 24 h later to produce quarter-embryos. The remaining demi-embryos, the quarter-embryos, and control intact embryos were cultured until Day 9, at which time they were assessed for quality and subjected to immunosurgery and differential staining to count inner cell mass (ICM) and trophectoderm cells. A higher proportion of demi-embryos than quarter-embryos was classified as viable (408/459, 89% vs 223/319, 70%, respectively; P < 0.001). Total cell numbers decreased with successive bisections, but the proportion of surviving cells found in the ICM was significantly (P < 0.05) higher in the best quality demi- and quarter-embryos (35 and 32%, respectively) than in the controls (22%). Transfer of all 12 quarter-embryos derived from 3 blastocysts, in pairs, into 6 recipient heifers resulted in 2 pregnancies, each with a single viable fetus at 90 d of gestation. The fetuses originated from 2 different blastocysts. The results suggest that bisection of intact IVP embryos into demi-embryos and bisection of those into quarter-embryos can increase the number of transferable embryos by as much as 178 and 235%, respectively.

Animals↗
PubMed1994

In vitro development of morulae from immature caprine oocytes.

The effects of medium supplementation with oestrous goat serum and glycoprotein hormones on caprine oocyte maturation in vitro (IVM) were evidenced by proportions of resulting ova completing in vitro fertilisation (IVF) and development to the morula stage. Oocyte-cumulus complexes (OCCs) were harvested in follicular fluid from 2-5 mm diameter follicles. Oocyte maturation took place during 27 h in TCM-199 supplemented with 20% oestrous goat serum, oestradiol-17 beta (1.0 microgram/ml), and either (a) 0.5 microgram FSH/ml, (b) 100 micrograms LH/ml, (c) 100 micrograms LH + 0.5 microgram FSH/ml, (d) 100 micrograms hCG + 0.5 microgram FSH/ml, (e) 0.5 microgram TSH/ml or (f) no added glycoprotein hormone (control). Of 353 immature oocytes cultured in seven experiments, 311 (88.1%) exhibited cumulus expansion at the end of the IVM interval; all normal-appearing OCCs were inseminated. In vitro insemination was with ejaculated sperm treated with heparin (10 micrograms/ml) and caffeine (0.4 microgram/ml). Proportions (%) of inseminated ova that were fertilised (cleaved) and that reached the morula stage after IVM with (a) FSH, (b) LH, (c) LH+FSH, (d) hCG + FSH, (e) TSH and (f) no added glycoprotein hormone were (a) 22/52 (42.3%) and 9/52 (17.3%), (b) 25/54 (46.3%) and 14/54 (25.9%), (c) 52/65 (80.0%) and 26/65 (40.0%), (d) 48/78 (61.5%) and 22/78 (28.2%), (e) 14/54 (25.9%) and 4/54 (7.4%), and (f) 11/50 (22.0%) and 1/50 (2.0%), respectively. All treatments yielded better results than IVM with no added glycoprotein hormone. After IVM with added LH+FSH higher proportions of oocytes were fertilised (p < 0.05), and higher proportions reached the morula stage (p < 0.05) when compared with other treatments.

Animal Husbandry↗
PubMed2000

Assessment of growth factor effects on post-thaw development of cryopreserved mouse morulae to the blastocyst stage.

The objective of this study was to assess the influence of specific factors on post-thaw development of mouse cryopreserved morulae. Thawed morulae (n = 206) were randomly distributed between 10 treatment groups: medium alone control (CT), Vero (VR) cells, leukaemia inhibitory factor (1 ng/ml), interleukin-6 (1 ng/ml), transforming growth factor (TGF) alpha (2 ng/ml), epidermal growth factor (EGF) (4 ng/ml), platelet-derived growth factor (1 ng/ml), insulin-like growth factor (IGF)-I (30 ng/ml), IGF-II (1 ng/ml) and TGFbeta (2 ng/ml). At 4, 8, 20, 30 and 48 h, a digitized image of each thawed embryo was captured and stored for later analysis. The following parameters were examined: blastocoel formation, blastocyst expansion, zona thickness and hatching. At termination of the experiment, cell number per embryo was determined by bisbenzimide staining. When contrasted to the medium alone control, co-culture consistently accelerated the development of frozen-thawed morulae to the hatched blastocyst stage, allowing embryos to recover rapidly from any damage sustained during the cryopreservation process. While no single growth factor/cytokine was able to completely mimic the results achieved with co-culture, all of the growth factors impacted positively on at least one of the morphological parameters studied. Cell proliferation was significantly stimulated by just 48 h exposure to growth factors, either through co-culture or by direct media supplementation. Co-culture again yielded the best results with a mean cell count of 217 +/- 76 cells per blastocyst as compared with 131 +/- 36 in control medium alone. Amongst the factors tested, IGF-I, IGF-II and EGF had the greatest impact, with mean cell counts of 172 +/- 50, 168 +/- 50 and 179 +/- 55 respectively. Whereas only 5% of CT embryos developed to blastocysts with > 200 cells, 51% of thawed embryos placed on co-culture monolayers and 25-32% of embryos cultured with IGF-I, IGF-II or EGF had > 200 cells. This study for the first time systematically describes the effect of culture regimen and growth factor additives on the post-thaw development of cryopreserved embryos.

Animals↗
PubMed2004

Experimental vitrification of human compacted morulae and early blastocysts using fine diameter plastic micropipettes.

BACKGROUND: Vitrification of human blastocysts has been successfully applied using grids, straws and cryoloops. We assessed the survival rate of human compacted morulae and early blastocysts vitrified in pipette tips with a smaller inner diameter and solution volume than the previously described open pulled straw (OPS) method. METHODS: Excess day 5 human embryos (n = 63) were experimentally vitrified in vessels. Embryos were incubated at 37 degrees C with sperm preparation medium (SPM) for 1 min, SPM + 7.5% ethylene glycol (EG)/dimethylsulphoxide (DMSO) for 3 min, and SPM + 16.5% EG + 16.5% DMSO + 0.67 mol/l sucrose for 25 s. They were then aspirated (0.5 microl) into a plastic micropipette tip (0.36 mm inner diameter), exposed to liquid nitrogen (LN(2)) vapour for 2 min before being placed into a pre-cooled cryotube, which was then closed and plunged into LN(2). Embryos were warmed and diluted using 0.33 mol/l and 0.2 mol/l sucrose. RESULTS: The survival rate for compacted morulae was 73% (22/30) and 82% (27/33) for early blastocysts. CONCLUSIONS: The survival rates of human compacted morulae and early blastocysts after vitrification with this simple technique are similar to those reported in the literature achieved by slow cooling and other vitrification protocols.

Blastocyst↗
PubMed1991

Decompaction and biopsy of late mouse morulae: assessment of in-vitro and in-vivo developmental potential.

The present study reports a biopsy technique on decompacted late mouse morulae. Zygotes were collected from hyperstimulated F1 hybrids (C57BL6j females x CBAca males) and cultured in modified Earle's balanced salt solution supplemented with 0.5% bovine serum albumin until the late morula stage (92 h post administration of human chorionic gonadotrophin). Decompaction was obtained by exposure of the embryos to Ca(2+)-Mg(2+)-free phosphate-buffered saline (PBS) or an aqueous solution of ethylene-diaminetetraacetic acid (EDTA) and glycine. Using micromanipulation, a single blastomere was aspirated without removal or softening of the zona. The impact of the different decompaction procedures and the biopsy technique was studied by vital staining, by in-vitro culture up to the early egg-cylinder staged and by the recovery of living mice after transfer to pseudopregnant foster mothers. Our investigations revealed no impact of decompaction and biopsy on immediate viability, as assessed by fluorescein diacetate staining. A significant reduction (P less than 0.05) in the number of mouse morulae that reached the early egg-cylinder stage in vitro was observed after the biopsy procedure. We observed that after this microbiopsy technique, successful pregnancies can be obtained but at a lower percentage compared to controls (P less than 0.01).

Animals↗
PubMed1993

In-vitro development of in-vivo produced rhesus monkey morulae and blastocysts to hatched, attached, and post-attached blastocyst stages: morphology and early secretion of chorionic gonadotrophin.

The earliest time of secretion of chorionic gonadotrophin (CG) by primate embryos and its role during preimplantation development and implantation are not clearly determined. We cultured in-vivo fertilized/developed zona-intact, morphologically normal morulae (n = 11) and early blastocysts (n = 11), freshly recovered (by non-surgical uterine flushing) on days 5 and 6 of pregnancy, respectively (day 0 = the day following LH surge), from non-superovulated naturally bred rhesus monkeys (Macaca mulatta). Embryos were cultured for a minimum of 24 days in dishes containing 1 ml of CMRL-1066 supplemented with 20% bovine fetal serum in a humidified atmosphere of 5% CO2 in air at 37 degrees C. The culture medium was changed every 48 h. The percentage of hatched blastocysts, developed from morulae and early blastocysts, was 90.9; elapsed times (mean +/- SEM) were 67.8 +/- 4.4 h (morula) and 37.8 +/- 3.6 h (blastocyst). The minimum number of Hoechst-stained cells/hatched blastocyst was 531. The mean diameter (+/- SEM) of cultured embryos increased from 180 microns at the beginning of culture to 374 +/- 28 and 450 +/- 19 microns at the fully expanded and hatched blastocyst stages, respectively. Hatched blastocysts continued to expand (maximum diameter: 1125 +/- 25 microns); after an additional 94-96 h they attached firmly to the serum-coated dishes and produced highly proliferating multinucleate trophectodermal cells, extending to a maximum diameter of 2-6 mm by 11-21 days of culture. Biologically active CG in embryo-grown, serial spent media samples was measured in a mouse Leydig cell bioassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

High survival of rabbit morulae after vitrification in an ethylene glycol-based solution by a simple method.

Rabbit morulae were exposed to a vitrification solution-modified PBS [PB1] medium containing 40% ethylene glycol + 18% Ficoll + 0.3 M sucrose (EFS) for 2, 5, or 10 min at 20 degrees C and were vitrified in liquid nitrogen. When morulae were rapidly warmed, 96% had an intact zona pellucida. When embryos were cultured after removal of the mucin coat, high proportions of them formed blastocoel (79-100%), but the percentage of embryos developed to fully expanded blastocysts decreased with increased exposure time 87%, 40%, and 17%). The survival rate of morulae vitrified after removal of the mucin coat was lower than that of mucin-intact embryos. To assess the development potential in vivo, 131 embryos were vitrified after 2 min of exposure to EFS solution; all the embryos were recovered and 120 were transferred to recipients without removal of the mucin coat, resulting in 78 (65%) full-term fetuses or young. This simple method, which yields high survival both in vitro and in vivo, will be of practical use for vitrifying rabbit embryos.

Animals↗
PubMed1992

Survival of mouse morulae vitrified in an ethylene glycol-based solution after exposure to the solution at various temperatures.

Mouse morulae were exposed in one step to a vitrification solution (EFS, a modified PBS containing 40% ethylene glycol, 18% Ficoll, and 0.3-M sucrose) at various temperatures, then cooled rapidly in liquid nitrogen, and then warmed rapidly. All of the embryos exposed to the EFS solution for 0.5 min at 25 degrees C before vitrification developed in culture. However, survival rates were lower if the duration of exposure was prolonged to 2, 5, or 10 min. At lower ambient temperatures (20, 10, and 5 degrees C), high survival rates were associated with longer exposure to the EFS solution. The toxicity of the EFS solution was also lower at lower temperatures. The toxic injury of morulae was manifested as decompaction of the blastomeres. Among the three additives in the EFS solution, ethylene glycol, which can cross cell membranes, was responsible for the toxicity. The results show that the optimum time for exposure of the embryos to the EFS solution before rapid cooling varies with the ambient temperature, i.e., 0.5 min at 25 degrees C, 0.5-5 min at 20 degrees C, 2-5 min at 10 degrees C, and 2-10 min at 5 degrees C. If they are exposed for an optimum period, almost all mouse morulae can survive vitrification (94-100%).

Animals↗
PubMed1988

Sexing of half-embryos produced by microsurgical bisection of mouse morulae and production of chimeric mouse of defined sex composition by aggregating two sexed half-embryos.

Using the halved morulae of mice obtained with microsurgical technique, the following two experiments were performed. 1) Sexing of half-embryos by chromosomal analysis and transfer of the half-embryos after determining the sex of the other monozygotic half. One half of the bisected embryo was cultured in Colcemid solution (0.04 micrograms/ml) to be ensured for chromosomal preparation. More than 50% (152/270) of the blastulated embryos from the halves could be sexed by direct sex chromosome analysis. Thirty-nine of the half-embryos of which the co-twin halves were sexed, were transplanted in to the uterine horns of 18 pseudopregnant mice, and twelve became pregnant. The autopsies of them on Day 18 to 20 of pregnancy, revealed the presence of 16 fetuses. The morphological sex of these fetuses thus obtained coincided completely with the previous judgement based on the chromosomal sexing. 2) Production of chimeras of defined sex composition by aggregating two half-morulae of defined sex. Out of 147 pairs of half-morulae of two different strains (ICR and C3H/He), which were replaced in pairs into empty zona pellucidae, 107 (72.8%) were aggregated successfully and developed in vitro into full expanding blastocysts of typical form. Among the 107 aggregate blastocysts, 31 were sexed for both component embryos by chromosomal analysis on the co-twin half-embryos. When these 31 blastocysts were transferred, 11 living offspring including 4 chimeras were obtained. Transfer of 12 male-male and 5 female-female aggregate blastocysts resulted in 8 males and 1 female, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

In vitro survival of murine morulae after quick freezing in the presence of chemically defined macromolecules and different cryoprotectants.

We studied the ability of frozen-thawed mouse morulae to develop in vitro when the cryoprotectant proteins were substituted with one of the following nonorganic macromolecules: polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and ficoll. We also determined how these agents interacted with 3 different cryoprotectants: glycerol (GLY), propylene glycol (PG), and ethylene glycol (EG). The influence of both of the above factors was measured on the basis of post-thaw morphological appearance, the percentage of development to the expanded blastocyst stage and the total cell count. Morulae (n=950) were collected from superovulated mice. Those classified as good or excellent were distributed among the 12 different freezing solutions, obtained by combining the 3 cryoprotectants with the 4 macromolecules (the 3 mentioned above, plus a control of 5% fetal calf serum) in phosphate buffered saline (PBS). Embryos frozen in PVA, PVP and ficoll tended to be a little difficult to recover from the straws. Development to the expanded blastocyst stage was significantly lower (P<0.05) in propylene glycol (43.6%) than in ethylene glycol (79.5%) or in glycerol (76.1%). Polyvinyl alcohol provided a higher survival rate when combined with glycerol (90.3) or ethylene glycol (95.0), but when it was combined with propylene glycol, only 56.5% of embryos survived after thawing. A positive interaction was observed between glycerol and PVA and between ethylene glycol and PVA or ficoll. The results indicate that fetal serum could be successfully substituted for any of the 3 chemically defined macromolecules. However, our findings also suggest that the use of PG as a cryoprotectant should be avoided when mouse morulae are frozen using the quick freezing method.

Journal Article↗