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At least 19 recordsLinked to original sources
PubMed2000

Ultrastructural morphometry of bovine compact morulae produced in vivo or in vitro.

The objective of this study was to compare the ultrastructure of bovine compact morulae produced in vivo or in vitro using morphometric analysis. Compact morulae produced in vivo were obtained from superovulated Holstein cows. Compact morulae produced in vitro were obtained from cumulus-oocyte complexes aspirated from ovaries of Holstein cows. The complexes were matured and fertilized in vitro. At 20 h postinsemination (hpi), zygotes were distributed into 1 of 3 culture media: 1) IVPS (in vitro produced with serum): TCM-199 + 10% estrous cow serum (ECS); 2) IVPSR (in vitro produced with serum restriction): TCM-199 + 1% BSA until 72 hpi followed by TCM-199 + 10% ECS from 72 to 144 hpi; 3) mSOF (modified synthetic oviductal fluid): SOF + 0.6% BSA. At 144 hpi, five grade 1 compact morulae from each of the four treatments were prepared for transmission electron microscopy. The volume density occupied by cellular components was determined by the point-count method using a sampling of seven to nine random micrographs from each compact morula. The volume density of lipid was greater (P < 0.05) in compact morulae from IVPS, IVPSR, and mSOF treatments compared with those produced in vivo. There was a reduced proportional volume of total mitochondria in compact morulae from the IVPS treatment compared with those produced in vivo (P < 0.05). For compact morulae from the IVPS culture treatment, the volume density of vacuoles was greater than that for compact morulae produced in vivo (P < 0.05). The cytoplasmic-to-nuclear ratio for compact morulae from the IVPS treatment was increased (P < 0.05) compared with the ratio for those produced in vivo. In conclusion, compact morulae produced in vitro differed ultrastructurally from those produced in vivo. Compact morulae produced in IVPS culture medium possessed the greatest deviations in cellular ultrastructure.

Animals↗
PubMed1999

Influences of retrieval stages and glutathione addition on post-thaw viability of quick frozen mouse morula during in vitro culture.

Effects of the embryo retrieval stages and addition of glutathione (GSH) on post-thaw development of mouse morula were evaluated in 2 consecutive experiments. In the first experiment, 1-, 2-, 3- to 4- and 5- to 8-cell stage embryos were collected and cultured to the morula stage in Whitten's medium containing 0.1 mM ethylenediaminetetraacetic acid (EDTA). The development rate of 1-cell embryos to the morula stage was lower than that of the other stages (P<0.01). The post-thaw development rate of the morulae obtained from in vitro culture of 1-, 2-, 3- to 4-, and 5- to 8-cell embryos and from in vivo embryos (control) to the blastocyst stage was 55.5, 84.9, 87.4, 90.1 and 90.8%, respectively. The post-thaw development rate of morula obtained from in vitro produced 1-cell embryos was significantly lower than from the other stages or from the in vivo counterparts (P<0.0001). In Experiment 2, the impact of GSH supplementation of the culture medium in the presence or absence of EDTA was evaluated for embryo development to the morula stage and post-thaw survival, using in the 2 x 2 factorial design. Although EDTA supplementation increased development rates to the morulae (P<0.01) stage, GSH did not have an influence on morula development. However, the presence of either GSH or EDTA in the culture medium supported development to the blastocyst stage (P<0.01) of in vitro produced morulae. These data demonstrate that 1-cell embryos from a blocking-strain mouse cultured in vitro to the morula stage have a lower development rate following freezing and thawing than embryos collected at the 2-cell or later stages. Addition of EDTA or GSH, individually or in combination, to the culture medium may improve the development rate of morula to blastocyst stage following cryopreservation.

Animals↗
PubMed1999

Effect of linoleic acid-albumin in the culture medium on freezing sensitivity of in vitro-produced bovine morulae.

The objective of this study was to improve the survival of in vitro-produced bovine morulae after cry opreservation. In Experiment 1, presumptive zygotes at 20 h post-insemination (hpi) were cultured in a mixture of modified synthetic oviduct fluid (m-SOF)/0.3% BSA and m-SOF/0.3% linoleic acid-albumin from bovine serum (LAA) at 39.0 degrees C in 5% O2, 5% CO2 and 90% N2 (final LAA concentration: 0, 0.01, 0.03, 0.1 or 0.3%). Morulae harvested at 138 hpi were frozen and thawed in m-PBS/0.3% BSA containing 1.5 M ethylene glycol and were cultured for 96 h in m-SOF/10% FBS to assess further development. The post-thaw survival of morulae derived from culture in 0.1% LAA (60%, P < 0.01) and in 0.03% LAA (55%, P < 0.05) was higher than that in 0% LAA (32%). Lowering the LAA concentration below 0.1% resulted in similar rates of morula development as in m-SOF/0.3% BSA. In Experiment 2, zygotes were cultured in m-SOF/0.1% LAA from 20 to 90 hpi and/or from 90 to 138 hpi. Post-thaw survival of morulae that had been exposed to LAA from 20 to 90 hpi (39%) or from 90 to 138 hpi (56%) was higher than that of morulae cultured without LAA from 20 to 138 hpi (12%, P < 0.02). These survival rates were lower than that of morulae cultured with LAA over a period of 20 to 138 hpi (76%, P < 0.001). The results indicate that cell-free culture of IVM/IVF bovine zygotes in m-SOF supplemented with LAA produces morula-stage embryos relatively tolerant to the process of freezing and thawing.

Animals↗
PubMed1997

The Drosophila gene morula inhibits mitotic functions in the endo cell cycle and the mitotic cell cycle.

In the endo cell cycle, rounds of DNA replication occur in the absence of mitosis, giving rise to polyploid or polytene cells. We show that the Drosophila morula gene is essential to maintain the absence of mitosis during the endo cycle. During oogenesis in wild-type Drosophila, nurse cells become polyploid and do not contain cyclin B protein. Nurse cells in female-sterile alleles of morula begin to become polyploid but revert to a mitotic-like state, condensing the chromosomes and forming spindles. In strong, larval lethal alleles of morula, the polytene ring gland cells also inappropriately regress into mitosis and form spindles. In addition to its role in the endo cycle, morula function is necessary for dividing cells to exit mitosis. Embryonic S-M cycles and the archetypal (G1-S-G2-M) cell cycle are both arrested in metaphase in different morula mutants. These phenotypes suggest that morula acts to block mitosis-promoting activity in both the endo cycle and at the metaphase/anaphase transition of the mitotic cycle. Consistent with this, we found cyclin B protein to be inappropriately present in morula mutant nurse cells. Thus morula serves a dual function as a cell cycle regulator that promotes exit from mitosis and maintains the absence of mitosis during the endo cycle, possibly by activating the cyclin destruction machinery.

Alleles↗
PubMed1993

Pluripotency of cultured rabbit inner cell mass cells detected by isozyme analysis and eye pigmentation of fetuses following injection into blastocysts or morulae.

Pluripotency of isolated rabbit inner cell masses (ICMs) and cultured (3 days) inner cell mass (ICM) cells was tested by injecting these donor cells into day 3.5 blastocysts (experiment 1) or day 3 morulae (experiment 2) to produce chimeric embryos. Injected (n = 107) and noninjected (n = 103) embryos were transferred to the opposite uterine horns of the same recipient females. Chimerism was determined by adenosine deaminase (ADA) isozyme analysis on fetal tissue and by eye pigmentation at midgestation. In experiment 1, 53% and 64%, respectively, of blastocysts injected with ICMs or cultured ICM cells developed to midgestation, compared with 52% and 48% for controls. Of these fetuses, four (31%) and one (6%), respectively, had ADA chimerism. In experiment 2, 38% and 62%, respectively, of the morulae injected with ICMs or cultured ICM cells developed to midgestation, compared with 46% and 56% for control morulae. Six (43%) chimeric fetuses from morulae injected with ICMs were detected by ADA analysis, but 12 (86%) chimeric fetuses were detected by eye pigmentation, indicating that eye pigmentation was a more sensitive marker for chimerism than our ADA assay. None of the 14 fetuses recovered after injecting morulae with cultured ICM cells were chimeric with either marker. No chimeras developed from control embryos. These studies demonstrate 1) that pregnancy rates are not compromised by injection of blastocysts or morulae with ICMs or cultured ICM cells, 2) that chimeric rabbit fetuses can be produced by injecting ICMs into either blastocysts or morulae, and 3) that cultured ICM cells can contribute to embryonic development when injected into blastocysts.

Animals↗
PubMed1990

Maintenance of compaction and adherent-type junctions in mouse morula-stage embryos.

Timed morulae of different stages of development were exposed to cytochalasin B causing depolymerisation of microfilaments and to ECCD-1 antibodies interacting with Ca2(+)-dependent adhesion molecules or cultured in the absence of calcium. All three treatments decompacted mid-morula-stage embryos within one hour. Late morulae were resistant to ECCD-1 antibody treatment and relatively resistant to calcium-free cultivation, but not to cytochalasin B treatment. Scanning electron microscopy revealed that the decompacting treatments not only loosened the interblastomere contacts but also resulted in rearrangement of the cell surface microvilli. Transmission electron microscopy showed that normal, untreated embryos had specialized membrane junctions in the most apical regions of the interblastomere contacts. Immunoelectron microscopy revealed that these apical junction areas contained vinculin, a protein typical of adherent junctions. Upon decompaction the apical junctions disappeared completely. When transferred back to the normal medium, the embryos rapidly started to recompact. Simultaneously the apical junctions and cell surface microvilli reassumed the organization characteristic of the morula stage. Late morulae that were resistant to treatment had normal apical junctional areas. During subcultivation in the normal medium, the treated morulae developed into morphologically normal blastocysts. These data indicate that adherent-type junctions and cell surface microvilli participate in the initiation and maintenance of compaction of morula-stage embryos.

Animals↗
PubMed1997

Relationship between timing of development, morula morphology, and cell allocation to inner cell mass and trophectoderm in in vitro-produced bovine embryos.

Noninvasive measurements of bovine embryo quality, such as timing of cleavage, morula morphology, blastocyst formation, and hatching ability, were linked with the number of inner cell mass (ICM) cells and trophectoderm (TE) cells of the resulting embryos. First, it was confirmed that fast-cleaving embryos proved to have significantly higher chances to reach advanced developmental stages vs. intermediate and slow cleavers (P = 0.01). They also showed significantly less fragmentation at the morula stage, implying the presence of more excellent morulae among fast-cleaving embryos (P < 0.05). Second, the quality of hatched blastocysts, resulting from morulae of different morphological grades, was examined by differential staining. The total cell and ICM cell numbers were significantly lower for hatched blastocysts developed from poor morulae compared to hatched blastocysts developed from excellent, good, or fair morulae. However, hatched blastocysts with < 10 ICM cells were seen in embryos belonging to all four morphological scores. Finally, it was found that timing of first cleavage was not significantly correlated with timing of blastocyst formation or with cell number of blastocysts. Timing of blastocyst formation, however, was significantly correlated with cell number: day 8 blastocysts had significantly lower total cell and ICM cell numbers than day 6 and day 7 blastocysts (P < 0.001). These results suggest that the quality of in vitro-produced bovine embryos is very variable and cannot be linked with a single criterion such as embryo morphology and/or hatching ability. Timing of blastocyst formation was the most valuable criterion with regard to embryonic differentiation.

Animals↗
PubMed1993

Embryonic stem cells derived from morulae, inner cell mass, and blastocysts of mink: comparisons of their pluripotencies.

A characterization of cell lines that we derived from morulae (three lines), blastocysts (two lines), and the inner cell mass (ICM) is given. The karyotype of all the lines was normal; the genotype of four lines was XX, and four lines were genotypically XY. The pluripotencies and commitment status of the derived lines were estimated. First, there were not less than two-thirds of cells in the populations of the lines derived from morulae and the ICM with both Xs active; 70-100% of cells of the blastocyst-derived lines had one of the Xs in an inactive state. The activity of glucose-6-phosphate dehydrogenase (G6PD) in the lines (genotype XX) derived from morulae and ICM was found to be twofold higher than in lines with genotype XY, and G6PD activity was the same in the blastocyst-derived XX lines and XY lines. Second, when injected intraperitoneally into athymic mice, morulae- and ICM-derived cells gave rise to simple and complex embryoid bodies (EB) resembling to typical "cystic" mouse EBs. Third, when injected subcutaneously to athymic mice, the ICM- or morula-derived cells gave rise to typical teratomas containing derivatives of the three germ layers and components of organogenesis. Comparisons of cell lines of different derivations demonstrated that the pluripotencies of the ES cells derived from morulae or the ICM are higher than those of blastocyst derivation.

Animals↗
PubMed1999

Fine structure of bovine morulae and blastocysts in vivo and in vitro.

The ultrastructure of bovine morulae and blastocysts developed from in vitro-matured and -fertilized oocytes in a serum-supplemented medium was compared with that of morulae and blastocysts collected non-surgically from superovulated cows. In the in vivo-derived morulae, two characteristic cells types could be identified by the electron-density of their cytoplasm and by their ultrastructural features. One type appeared light in color with low electron-dense cytoplasm. These cells were located in the peripheral layer of the cluster of blastomeres, possessed numerous cellular organelles such as mitochondria and Golgi apparatus and had microvilli projecting into the perivitelline space. The other cell type was distinguished by cytoplasm that stained more densely than that of the lighter-appearing cells. The darker-appearing cells generally possessed fewer organelles than the lighter cells, but many lysosome-like structures were present in the cytoplasm. The in vitro-developed morulae also contained two types of cells similar to those observed in the in vivo morulae. However, most of the in vitro-developed cells possessed numerous lipid droplets and contained fewer lysosome-like structures than the cells of the in vivo-derived morulae. The blastocysts, both in vivo and in vitro, showed a clear differentiation of trophoblast cells and inner cell mass (ICM)-cells. In the in vivo-derived blastocyst, the apical membrane of trophoblast cells was covered with large, numerous microvilli and well-developed junctional complexes were observed. Lipid droplets were present in the cytoplasm of trophoblast and ICM-cells but were not abundant. In vitro-developed blastocysts showed less well-developed junctional complexes between trophoblast cells, less well-developed apical microvilli on the trophoblast cells, and contained large numbers of lipid droplets. This accumulation of lipid droplets was higher in the trophoblast cells than in the ICM-cells. The zonae pellucidae of in vitro-developed embryos were thinner than that of the in vivo-derived embryos. This study demonstrates conspicuous differences in the ultrastructural features between the in vivo-derived and in vitro-developed embryos, suggesting that the ultrastructure may reflect the various physiological anomalies observed in previous studies.

Animals↗
PubMed1981

Immunofluorescence techniques for determining the numbers of inner and outer blastomeres in mouse morulae.

Methods are described for distinguishing inner and outer blastomeres of compact 8- to 32-cell mouse morulae. The first involves the selective labelling by immunofluorescent reagents of the exposed surface of the compact morula, disaggregation of the morula into single blastomeres and separation of these blastomeres into partially labelled (presumptive outer) and unlabeled (presumptive inner) populations. The second involves labelling blastomeres after disaggregation and is based on the recent observation that the sera on an isolated outer blastomere which originally contributed to the exposed surface of the intact morula labels more intensely than the remaining (non-exposed) surface of the blastomere. Analysis of the labelling patterns obtained from individual disaggregated morulae indicated that inner blastomeres were absent from compact 8-cell morulae, but increased in number throughout the next cleavage division until at the 16-cell stage the mean number of these blastomeres varied from 4.6 to 6.6 (with a range of 1--8) depending on the technique used. At later stages, the numbers of inner blastomeres can probably be accounted for by division of the inner cells at the 16-cell stage.

Animals↗
PubMed1991

Successful co-culture of 1-4-cell cattle ova to the morula or blastocyst stage.

Bovine ova (n = 326) collected at the 1-4-cell stage were cultured in TCM-199 + 10% foetal calf serum with or without oviducal cells. The bovine oviducal cells were collected and seeded either on the day of ovum recovery (BOC-0) or 3 days earlier (BOC-3). In Exp. 1, the effect of age of oviducal cells in co-culture on ovum development was examined. In the BOC-0 and BOC-3 treatments, respectively, 36/46 (78%) and 30/37 (81%) of ova developed to morulae or blastocysts, while no ova developed past the 8-16-cell stage in the absence of oviducal cells. In Exp. 2, the effect of age of oviducal cells and of physical contact between the oviducal cells and ova on ovum development was examined. In the BOC-0 and BOC-3 treatments, respectively, 29/42 (69%) and 23/43 (53%) of the ova developed to morulae or blastocysts, while 1/42 (2%) developed to the morula stage in the absence of oviducal cells. Physical separation of the ova using a microporous membrane inserted between the oviducal cells and the ova did not affect ovum development, with 26/42 (62%) and 22/42 (52%) of ova developing to morulae or blastocysts in the BOC-0 and BOC-3 treatments, respectively. A high proportion of the morulae and blastocysts in Exp. 1 (57/66, 86%) and Exp. 2 (67/100, 67%) were of quality grades 1 or 2, with mean nuclei counts of 85 for morulae and 111 for blastocysts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Sex-dependent loss of bisected bovine morulae after culture and freezing.

The objective of this study was to determine the post-transfer survival rate of bovine embryos cultured between the time of bisection and freezing. In this experiment 158 morulae were bisected and both portions were cultured for 24-44 h either in vivo after transfer to sheep oviducts (n = 80 morulae) or in vitro (n = 78 morulae) in Ham's F10 medium with 20% fetal calf serum, with bovine oviduct cells or in medium collected from oviduct cultures (conditioned medium). After culture, half of each morula was fixed for cytogenetic sex determination (n = 125) and the other half was frozen. The frozen halves were later thawed and transferred (n = 115) to recipients, who were, if pregnant, slaughtered to determine the sex of the fetus. The culture resulted in better pregnancy rates than those previously reported for embryos frozen immediately after bisection. The sex of 49 (33 males, 16 females) of the fixed demi-morulae was determined, and 38 of the transferred demi-morulae established pregnancies (23 males, 10 females and 5 fetuses that were not recovered). The male:female ratio in in vivo and in vitro culture groups was significantly different from the expected ratio of 1:1 and suggests that manipulation and culture of embryos results in a preferential loss of female embryos.

Animals↗
PubMed1998

Superovulation of rabbits with FSH alters in vivo development of vitrified morulae.

Morulae were flushed from the oviducts and uteri of New Zealand White (NZW) rabbits superovulated with either 6 (3 d) or 8 (4 d) injections of FSH and from non-superovulated controls. The percentages of embryos recovered from 4 d (100%, n = 8) donors was significantly higher (P < 0.01) than that of 3 d (76%, n = 16) and control (87%, n = 22) donors. Overall, fertilization rates were significantly lower for the 3 d embryos (P < 0.01). Most (86 to 90%) morulae were morphologically suitable for vitrification in an ethylene glycol-based solution. Following storage in liquid nitrogen, morulae were rapidly thawed and transferred to the uteri of pseudopregnant recipients. The total number of kits born for the 3 d, 4 d, and control groups was 40, 61 and 48, respectively. The percentage of live kits from morulae transferred was significantly lower for the 3 d (20%, n = 201) than either the 4 d (36%, n = 169; P < 0.01) or the control (31%, n = 157; P < 0.05) group. The mean number of kits born/recipient for the 3 d (2.4 +/- 2.9), 4 d (4.7 +/- 3.5), and control (3.0 +/- 2.2) protocols did not differ (P > 0.05). The estimated overall efficiency of producing kits based on normal morulae collected for control and 4 d groups, however, was nearly two-fold that for females given 6 FSH treatments. We conclude that the 4 d FSH superovulation regimen enhances the efficiency of rabbit reproductive biotechnology after embryo cryopreservation. These findings have important implications for rabbit colony management using embryo cryopreservation.

Animals↗
PubMed1996

Synergistic effect of alanine and glycine on bovine embryos cultured in a chemically defined medium and amino acid uptake by vitro-produced bovine morulae and blastocysts.

The effect of glycine and alanine on the development of 2- to 4-cell bovine embryos, and amino acid uptake by bovine morulae and blastocysts, were examined through the use of a chemically defined medium. Bovine embryos at 2- to 4-cell stages were prepared by in vitro maturation and fertilization and cultured in a synthetic oviduct fluid medium (SOFM) containing polyvinyl alcohol (PVA) instead of BSA in order to examine the effect of amino acids. Morulae or blastocysts obtained from culture in SOFM containing BSA were cultured for 10 h in SOFM containing PVA to determine amino acid uptake. The combination of essential and nonessential amino acids with or without glutamine improved development to the blastocyst stage over that observed in the control (34% or 32% vs. 19%, respectively; p < 0.05). The optimal supplemental concentrations were 5 mM for alanine and 10 mM for glycine. At these concentrations, development to blastocysts was enhanced by the addition of alanine or glycine independently (35% or 36% vs. 26%, respectively; p < 0.05); the combined addition of alanine and glycine greatly (p < 0.01) improved proportions of blastocysts (45% vs. 26%) and hatched blastocysts (10% vs. 2%) compared to those obtained in the control. Addition of glycine with or without alanine to culture medium significantly increased cell number per blastocyst over that in the control (137 +/- 5 or 131 +/- 5 vs. 106 +/- 4, respectively; p < 0.01). Bovine morulae and blastocysts depleted aspartate, serine, and glutamate at a highly significant rate (p < 0.001) and arginine at a significant rate (p < 0.05), and produced alanine at a highly significant rate (p < 0.001) when cultured in medium containing 20 essential and nonessential amino acids. Serine, asparagine, glycine, alanine, and glutamine were highly (p < 0.001) produced by bovine morulae and blastocysts cultured in a medium containing essential amino acids without glutamine. These results indicate that alanine and glycine in a defined medium synergistically improve development of in vitro-produced bovine embryos, and also that bovine morulae and blastocysts prefer aspartate, glutamate, serine, and arginine and produce glutamine and several nonessential amino acids (serine, asparagine, alanine, and glycine).

Alanine↗
PubMed1998

Antibodies with the cell-type specificity to the morula cells of the solitary ascidians Styela rustica and Boltenia echinata.

The separation of the blood cells of Styela rustica (Styelidae, Stolidobranchiae) in discontinuous Percoll gradient showed 4 fractions. The 4th and bottom most fraction contained 90-100% of morula cells. The protein composition of the morula cell fraction revealed on SDS-PAGE showed two major proteins with m.w. 47 and 26 kDa. These proteins were heavily positively charged. Polyclonal antiserums against these proteins were raised. Each antiserum reacted with both proteins only in morula cells on the blot after SDS-PAGE and stained the proper protein without crossreaction on the blot after AU-PAGE. The only type of cells stained with antibodies in circulating blood, in the tunic and on the tunic wound surface in paraffin sections of another species Boltenia echinata (Pyuridae, Stolidobranchiae) were morula cells. The morula-type specific antibodies obtained recognized major positively charged proteins which were apparently structural substrates for the phenoloxidase tanning.

Animals↗
PubMed1984

Production of monozygotic mouse twins from microsurgically bisected morulae.

Mouse monozygotic twins were produced by bisection of the compacted morulae and transfer of the pairs of half-embryos after culture in vitro. The compacted morulae (about 16 cells) were microsurgically bisected, using a fine glass needle attached to a micromanipulator, without any supporting micro-instruments, after pretreatment for zona-softening and decompaction. About 80% of the morulae were bisected without visible cell damage. After 20 h in culture, the half-embryos were classified morphologically as eu-blastocysts, pseudo-blastocysts, or trophectodermal vesicles or non-integrated forms. After culture of 131 pairs of bisected morulae, 75 (57.3%) pairs of eu-blastocysts, 20 (15.3%) pairs comprising a eu-blastocyst and pseudo-blastocyst, and 9 (6.9%) pairs of pseudo-blastocysts, were obtained. The pseudo-blastocysts were considered to be derived from half-morulae in which some blastomeres were destroyed or dissociated as a result of micromanipulation. From 30 pairs of eu-blastocysts transferred to 21 recipients, 5 twin fetuses on Day 17 (18 pairs/9 recipients) and 3 twin male young (12 pairs/12 recipients) were obtained. Survival rate of the twin-embryo pairs was 27.8% at autopsy and 25.0% at term. None of the 20 pairs of pseudo-blastocysts transferred to 10 recipients gave rise to normal conceptuses.

Animals↗
PubMed1982

Protection of non-cellular investments of rabbit morulae stored at--196 degrees C.

The non-cellular investments were damaged in only 2.8% of rabbit morulae frozen/ thawed in plastic straws. Similar results (4.8%) were obtained with glass ampoules only when morulae were slowly frozen and slowly thawed in siliconized ampoules. Freezing/thawing by other methods and the use of untreated ampoules resulted in high incidence of embryos with damaged investments (41-61%). Morulae frozen/thawed by a method allowing an almost complete elimination of investment injury displayed high survival when slowly frozen and rapidly thawed (90.7%) while slow freezing and slow thawing decreased survival (74.5%). Morulae subjected to rapid freezing were for the first time successfully stored at--196 degrees C. After rapid thawing 59.6% morulae survived. The mechanism of damage to the non-cellular investments of rabbit embryos is discussed.

Animals↗
PubMed1976

Nucleotides in embryos in the stages of morula, gastrula, and neurula.

Levels of nucleotides and sugar nucleotides in embryos of Bufo arenarum at the stages of morula, gastrula, and neurula have been measured. The total amounts of purine nucleoside diphosphates decreased from morula to gastrula, but increased sharply from gastrula to neurula. The levels of ADP followed this pattern, but those of GDP did not change significantly through the three stages. Purine nucleoside triphosphate levels, which had increased immediately after fertilization, remained almost constant through morula, gastrula, and neurula. As with the purine nucleoside diphosphates, the adenine nucleotide decreased from morula to gastrula, and increased from gastrula to neurula. In contrast, the level of GTP showed a sharp maximum at gastrula. The total pyrimidine nucleoside triphosphate did not change significantly from morula through neurula. As in previous stages of development, only uridine sugar nucleotides were detected. A sharp increase of the galactosyl ester of nucleotides was found at gastrula.

Adenosine Diphosphate↗