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W F Rall

Publications and source records attributed to W F Rall.

At least 19 recordsLinked to original sources
PubMed2000

Factors affecting the efficiency of embryo cryopreservation and rederivation of rat and mouse models.

The efficiency of embryo banking for rat and mouse models of human disease and normal biological processes depends on the ease of obtaining embryos. Authors report on the effect of genotype on embryo production and rederivation. In an effort to establish banks of cryopreserved embryos, they provide two databases for comparing banking efficiency: one that contains the embryo collection results from approximately 11,000 rat embryo donors (111 models) and another that contains the embryo collection results from 4,023 mouse embryo donors (57 induced mutant models). The genotype of donor females affected the efficiency of embryo collection in two ways. First, the proportion of females yielding embryos varied markedly among genotypes (rats: 16-100 %, mean =71 %; mice: 24-95 %, mean =65 %). Second, the mean number of embryos recovered from females yielding embryos varied considerably (rats: 4-10.6, mean =7.8; mice 5.3-32.2, mean =13.7). Genotype also affected the efficiency of rederivation of banked rat and mouse embryos models by embryo transfer. For rats, thawed embryos (n =684) from 33 genotypes were transferred into 66 recipient females (pregnancy rate, 78 %). The average rate of developing live newborns for individual rat genotypes was 30 % with a range of 10 to 58 %. For mice, thawed embryos (n =2,064) from 59 genotypes were transferred into 119 pseudopregnant females (pregnancy rate: 76 %). The average rate of development of individual mouse genotypes was 33 % with a range of 11 to 53 %. This analysis demonstrates that genotype is an important consideration when planning embryo banking programs.

Animals↗
PubMed1999

Prolonged mating in prairie voles (Microtus ochrogaster) increases likelihood of ovulation and embryo number.

Prairie voles are induced ovulators that mate frequently in brief bouts over a period of approximately 24 h. We examined 1) impact of mating duration on ovulation and embryo number, 2) incidence of fertilization, 3) temporal pattern of embryo development, 4) embryo progression through the reproductive tract over time, and 5) embryo development in culture. Mating was videotaped to determine first copulation, and the ovaries were examined and the reproductive tracts flushed at 6, 8, 10, 12, 16, 20, and 24 h and 2, 3, and 4 days after first copulation. The number of mature follicles and fresh corpora lutea and the number and developmental stage of embryos were quantified. One, two-, and four-cell embryos were cultured in Whitten's medium. Mature follicles were present at the earliest time examined (6 h). Thirty-eight percent of females that had been paired for < 12 h after the first copulation ovulated, whereas all females paired >/= 12 h after the first copulation ovulated. Virtually all (> 99%) oocytes recovered from females paired for >/= 12 h after first copulation were fertilized. Pairing time after first copulation and mean copulation-bout duration were significant (p < 0.05) determinants of embryo number. Embryos entered the uterine horns and implanted on Days 3 and 4, respectively, after first copulation (Day 0). Embryos cultured in vitro underwent approximately one cell division per day, a rate similar to that in vivo. We conclude that prairie voles ovulate reliably after pairing for >/= 12 h, although some females showed exceptional sensitivity not predicted by the variables quantified. Prolonged mating for longer than 12 h increased the total embryos produced. This mechanism likely has adaptive significance for increasing offspring number.

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↗
PubMed1997

Water distribution and permeability of zebrafish embryos, Brachydanio rerio.

Teleost embryos have not been successfully cryopreserved. To formulate successful cryopreservation protocols, the distribution and cellular permeability to water must be understood. In this paper, the zebrafish (Brachydanio rerio) was used as a model for basic studies of the distribution to permeability to water. These embryos are a complex multi-compartmental system composed of two membrane-limited compartments, a large yolk (surrounded by the yolk syncytial layer) and differentiating blastoderm cells (each surrounded by a plasma membrane). Due to the complexity of this system, a variety of techniques, including magnetic resonance microscopy and electron spin resonance, was used to measure the water in these compartments. Cellular water was distributed unequally in each compartment. At the 6-somite stage, the percent water (V/V) was distributed as follows: total in embryo = 74%, total in yolk = 42%, and total in blastoderm = 82%. A one-compartment model was used to analyze kinetic, osmotic shrinkage data and determine a phenomenological water permeability parameter, Lp, assuming intracellular isosmotic compartments of either 40 or 300 mosm. This analysis revealed that the membrane permeability changed (P < 0.05) during development. During the 75% epiboly to 3-somite stage, the mean membrane permeability remained constant (Lp = 0.022 +/- 0.002 micron x min-1atm-1 [mean +/- S.E.M.] assuming isosmotic is 40 mosm or Lp = 0.049 +/- 0.008 micron x min-1atm-1 assuming isosmotic is 300 mosm). However, at the 6-somite stage, Lp increased twofold (Lp = 0.040 +/- 0.004 micron x min-1atm-1 assuming isosmotic is 40 mosm or Lp = 0.100 +/- 0.017 micron x min-1atm-1 assuming isosmotic is 300 mosm). Therefore, the low permeability of the zebrafish embryo coupled with its large size (and consequent low area to volume ratio) led to a very slow osmotic response that should be considered before formulating cryopreservation protocols.

Animals↗
PubMed1997

Chill sensitivity and cryoprotectant permeability of dechorionated zebrafish embryos, Brachydanio rerio.

The zebrafish (Brachydanio rerio) was used as a model for basic studies of the chilling sensitivity, permeability and toxicity of cryoprotectants. In both intact and dechorionated embryos, early-stage embryos (1.25, 1.5, 1.75, and 2 h) were more susceptible (P < 0.05) to chilling injury at 0 degrees C than late-stage embryos (50, 75, and 100% epiboly and three-somite stage). Moreover, enzymatic removal of the chorion did not alter (P > 0.05) this pattern of sensitivity to chilling. Eight-hour zebrafish embryos tolerated short-term exposures to temperatures ranging from 4 to 23 degrees C for 3.5 h with no detrimental developmental effects. The permeability of dechorionated embryos to cryoprotectants was examined by measuring the kinetics of volumetric change at various developmental stages (16 cells to six somites or ca. 1.25 to 14 h postfertilization) at 28.5 degrees C. The dechorionated zebrafish embryo is composed of two complex cellular compartments (i.e., a large yolk and the developing blastoderm). From 40 to 100% epiboly, the volumes of yolk and blastoderm remained constant, ca. 82 and 18%, respectively. However, these volumes changed rapidly after epiboly. For example, at the six-somite stage, the yolk composed 61% of the total volume, whereas the blastoderm composed 39%. When three- and six-somite embryos were placed in 1.5 and 2.0 M cryoprotectants (dimethyl sulfoxide and propylene glycol), osmometric measurement of volume changes indicated no permeation of the cryoprotectants. However, some permeation was observed for six-somite embryos immersed in a 2.0 M methanol solution, but not for 3-somite embryos. For up to 30 min at room temperature, these cryoprotectant solutions were toxic to zebrafish embryos; however, 1.5 M glycerol and ethylene glycol solutions were. We conclude that the complex nature of the zebrafish embryo reduces the effectiveness and predictive value of light microscopical measurements for cryoprotectant permeability studies.

Animals↗
PubMed1995

Effect of genotype on the efficiency of mouse embryo cryopreservation by vitrification or slow freezing methods.

We examined possible genotype effects on the survival of 8- to 16-cell mouse embryos isolated from four inbred strains (C57BL/6N, BALB/cAnN, DBA/2N, and C3H/HeN), a outbred stock (ICR), and various crosses after cryopreservation by vitrification or conventional slow freezing using glycerol solutions. The rates of in vitro development of C57BL/6N, BALB/cAnN, C3H/HeN, and ICR embryos to expanded blastocysts ranged from 86% to 94% after slow freezing and 85% to 97% after vitrification. The cryopreservation method did not significantly influence in vitro embryo survival after thawing (P > 0.05). Although genotype significantly influenced the in vitro survival of embryos (P = 0.008), this presumably resulted from an increased difficulty in assessing the quality grade of C3H/HeN embryos prior to cryopreservation. The rates in vivo development of C57BL/6N, BALB/cAnN, C3H/HeN, DBA/2N, and ICR embryos to normal day 18-19 fetuses ranged from 19% to 64% after slow freezing and from 18% to 63% after vitrification. The in vivo development of cryopreserved embryos was significantly influenced by cryopreservation method and genotype (P = 0.01 and P = 0.001, respectively). Vitrification yielded significantly higher rates of in vivo development than that after slow freezing (P > 0.05). In vivo development rates of DBA/2N and ICR female X B6D2F1 male embryos after cryopreservation were significantly higher than that of embryos from BALB/cAnN and C3H/HeN mice (P < 0.05). These results indicate that parental genotype exerts little or no effect on the ability of embryos to develop in vitro after vitrification or slow freezing. Differences in the ability of cryopreserved embryos to develop normally in vivo may reflect inherent genotype related differences in their post-implantation developmental potential and not their sensitivity to cryoinjury.

Animals↗
PubMed1995

Comparison of the efficacy of conventional slow freezing and rapid cryopreservation methods for bovine embryos.

Day 7 bovine morulae and early blastocysts were randomly assigned to one of four cryopreservation methods: (i) a modified conventional controlled slow freezing and stepwise dilution after thawing; and three methods which enable direct transfer of the embryo into the recipient upon thawing: (ii) conventional controlled slow freezing and a modification of a one-step procedure, (iii) vitrification with 6.5 M glycerol plus 6% BSA (w/v), and (iv) vitrification with 25% glycerol (v/v) and 25% propanediol (v/v). In a comparative in vitro study, the percentage of grade 1 and 2 embryos developing into expanded blastocysts in culture for cryopreservation methods 1-4 were, respectively, 53% (29/55), 33% (20/61), 44% (26/59), and 51% (17/33). Method 2 yielded a significantly lower survival rate than methods 1 (P < 0.1) and 4 (P < 0.05) and was excluded from a subsequent test of in vivo development. Pregnancy rates (Day 60) after transfer of embryos cryopreserved by methods 1, 3, and 4 were, respectively, 59% (20/34), 43% (17/40), and 24% (5/21). Method 4 yielded a significantly lower pregnancy rate than method 1 (P < 0.05). Method 3, however, did not yield a statistically different pregnancy rate (P > 0.1) when compared to method 1. Method 3 has considerable promise in providing a successful method for the cryopreservation of bovine embryos that (i) reduces the time required for equilibration and cooling, (ii) provides for simple and rapid one-step dilution of cryoprotectant after thawing, and (iii) enables more embryos to be thawed and transferred per unit time.

Animals↗
PubMed1994

High in vitro and in vivo survival of day 3 mouse embryos vitrified or frozen in a non-toxic solution of glycerol and albumin.

A vitrification solution consisting of 6.5 mol glycerol l-1 and 6% (w/v) BSA in a modified Dulbecco's PBS (designated solution VS3a) was examined for the cryopreservation of 8-12-cell mouse embryos. Solution VS3a vitrified when cooled to -196 degrees C at rates of 10-2500 degrees C min-1 and vitrified suspensions did not crystallize when warmed at 200 or 2000 degrees C min-1. However, slow cooling at 5 degrees C min-1 or slow warming at 20 degrees C min-1 resulted in visible crystallization of solution VS3a. Embryos were equilibrated in solution VS3a in three steps at room temperature and placed into a 0.25 ml plastic straw in a way that permitted in-straw dilution with 1 mol sucrose l-1. Embryos equilibrated in solution VS3a and diluted immediately exhibited high rates of development in vitro to blastocysts (> 90%) if the total time of exposure to 100% solution VS3a did not exceed 5 min. Embryos exhibited high rates of development in vitro (75-97%) when equilibrated in 100% solution VS3a for 1 min and then cryopreserved using all combinations of three rates of cooling (5200 or 2500 degrees C min-1) and three rates of warming (20,000 or 2000 degrees C min-1). Although embryo suspensions visibly crystallized during slow cooling at 5 degrees C min-1, the rate of cooling was not a significant source of variance (P > 0.26). However, the rate of warming was found to have a small but significant effect on embryo survival (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Successful intrauterine insemination of Eld's deer (Cervus eldi thamin) with frozen-thawed spermatozoa.

This study tested the efficacy of assisted reproduction (synchronization of oestrus and intrauterine artificial insemination (AI)) in contributing to the captive propagation of an endangered species, the Eld's deer (Cervus eldi thamin). Semen was collected from males preselected on the basis of under-represented genotype. Motility of spermatozoa after thawing from ejaculates diluted with BF5F extender (8% glycerol), frozen on dry ice in 0.5 ml straws and stored in liquid nitrogen was 60-70%. Intravaginal progesterone-releasing devices (controlled internal drug release, CIDR-type G) were inserted into 20 adult Eld's deer hinds for 14 days. In all hinds, semen (7.5-10 x 10(6) motile spermatozoa per uterine horn) was deposited by laparoscopy performed 70 h after removal of the CIDR device. Ovarian activity, before and after AI, was monitored by analysing pregnanediol-3 alpha-glucuronide (PdG) concentrations in voided urine collected three to seven times per week. During the period of CIDR device insertion, urinary PdG profiles were equal to, or above, normal luteal phase concentrations in all hinds. Within 48 h of device withdrawal, PdG concentrations returned to baseline values in 17 of the 20 females, and the onset of behavioural oestrus occurred at this time in 12 hinds. On the basis of sustained increases in urinary PdG, 9 of the 20 hinds were diagnosed as pregnant by 90 days after AI, all of which delivered offspring after a mean gestation of 241.1 days (range, 235-245). Seven singletons (two females, five males) were born alive and survived, and one singleton and one set of twins were stillborn (three females).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Cryopreservation of Drosophila melanogaster embryos.

There is an urgent need to preserve the ever-increasing number (greater than 30,000) of different genetic strains of D. melanogaster that are maintained in national and international stock centres and in the laboratories of individual investigators. In all cases, the stocks are maintained as adult populations and require transfer to fresh medium every two to four weeks. This is not only costly in terms of materials, labour and space, but unique strains are vulnerable to accidental loss, contamination, and changes in genotype that can occur during continuous culture through mutation, genetic drift or selection. Although cryopreservation of Drosophila germ-plasm would be an enormous advantage, many attempts using conventional procedures have been unsuccessful. D. melanogaster embryos are refractory to conventional cryopreservation procedures because of the contravening conditions required to minimize mortality resulting from both intracellular ice formation and chilling injury at subzero temperatures. To overcome these obstacles, we have developed a vitrification procedure that precludes intracellular ice formation so that the embryos can be cooled and warmed at ultra-rapid rates to minimize chilling injury, and have recovered viable embryos following storage in liquid nitrogen. In a series of 53 experiments, a total of 3,711 larvae emerged from 17,280 eggs that were cooled in liquid nitrogen (18.4 +/- 8.8%). Further, using a subset from this population, approximately 3% of the surviving larvae (24/800) developed into adults. These adults were fertile and produced an F1 generation.

Animals↗
PubMed1988

Pregnancy resulting from cryopreserved human embryos using a one-step in situ dilution procedure.

In vitro fertilization and embryo transfer require the use of hormonal manipulation and surgery that may reduce the receptivity of the patient's uterus during the stimulated cycle. Cryopreservation of human embryos eliminates the need for immediate transfer, permitting them to be stored until they can be transferred during subsequent unstimulated cycles. Embryo cryopreservation is an established procedure in the breeding of laboratory and domestic animals, but has only recently been applied to humans. We report on a pregnancy using a simple cryopreservation procedure that permits embryos to be diluted out of the cryoprotectant solution without removing them from the plastic straw in which they were cryopreserved.

Adult↗
PubMed1987

Factors affecting the survival of mouse embryos cryopreserved by vitrification.

Preimplantation stage mouse embryos have been used to examine the response of a simple multicellular system to cryopreservation by the complete vitrification of the suspension. Successful vitrification requires the use of a solution of cryoprotectants that is sufficiently concentrated to supercool and solidify into a glass at practicable cooling rates. Factors that influence the survival of embryos include the concentration and composition of the vitrification solution, the procedure used to equilibrate embryos in this solution, the cooling and warming conditions, and the procedure used to dilute embryos from the vitrification solution. High rates of survival are obtained when embryos are dehydrated prior to vitrification in solutions composed of saline plus multimolar concentrations of either mixtures of permeating cryoprotectants (e.g. dimethyl sulphoxide-acetamide-propylene glycol) or single permeating cryoprotectants (propylene glycol or glycerol). Full permeation of cryoprotectants into the cells is not necessary and may lead to chemical toxicity and osmotic injury. Partial permeation and osmotic shrinkage concentrates the endogenous cytoplasmic macromolecules and greatly increases the likelihood of intracellular vitrification. Vitrification is a practical approach for embryo cryopreservation and offers new opportunities to examine fundamental aspects of cryoprotection and cryoinjury in the absence of freezing.

Animals↗
PubMed1987

Development of mouse embryos cryopreserved by vitrification.

Eight-cell mouse embryos were cryopreserved by vitrification in a concentrated solution of dimethylsulphoxide, acetamide, propylene glycol and polyethylene glycol. This solution (designated VS1) does not crystallize when cooled to subzero temperatures but instead forms a glassy transparent solid. Embryos were exposed in three steps to a stock VS1 solution or a saline solution containing 90% of the cryoprotectants in the stock VS1 (90% VS1) and then the suspensions were vitrified by rapid cooling in liquid nitrogen. Of 568 embryos vitrified in 90% VS1, 80% developed in vitro and 98 normal fetuses or young (17% of the total) were produced after transfer to pseudopregnant recipients. By contrast, 22% of 153 embryos vitrified in the stock VS1 developed in vitro, but only one normal fetus was obtained after transfer. These results demonstrate that normal fetuses and young can be produced from embryos cryopreserved by the simple and rapid method of vitrification.

Animals↗
PubMed1984

Kinetics of water loss and the likelihood of intracellular freezing in mouse ova. Influence of the method of calculating the temperature dependence of water permeability.

To avoid intracellular freezing and its usually lethal consequences, cells must lose their freezable water before reaching their ice-nucleation temperature. One major factor determining the rate of water loss is the temperature dependence of the water permeability, Lp (hydraulic conductivity). Because of the paucity of water permeability measurements at subzero temperatures, that temperature dependence has usually been extrapolated from above-zero measurements. The extrapolation has often been based on an exponential dependence of Lp on temperature. This paper compares the kinetics of water loss based on that extrapolation with that based on an Arrhenius relation between Lp and temperature, and finds substantial differences below -20 to -25 degrees C. Since the ice-nucleation temperature of mouse ova in the cryoprotectants DMSO and glycerol is usually below -30 degrees C, the Arrhenius form of the water-loss equation was used to compute the extent of supercooling in ova cooled at rates between 1 and 8 degrees C/min and the consequent likelihood of intracellular freezing. The predicted likelihood agrees well with that previously observed. The water-loss equation was also used to compute the volumes of ova as a function of cooling rate and temperature. The computed cell volumes agree qualitatively with previously observed volumes, but differ quantitatively.

Animals↗
PubMed1984

Effect of warming rate on mouse embryos frozen and thawed in glycerol.

Mouse embryos (8-cell) fully equilibrated in 1.5 M-glycerol were cooled slowly (0.5 degrees C/min) to temperatures between - 7.5 and - 80 degrees C before rapid cooling and storage in liquid nitrogen (-196 degrees C). Some embryos survived rapid warming (approximately 500 degrees C/min) irrespective of the temperature at which slow cooling was terminated. However, the highest levels of survival of rapidly warmed embryos were observed when slow cooling was terminated between -25 and -80 degrees C (74-86%). In contrast, high survival (75-86%) was obtained after slow warming (approximately 2 degrees C/min) only when slow cooling was continued to -55 degrees C or below before transfer into liquid N2. Injury to embryos cooled slowly to -30 degrees C and then rapidly to -196 degrees C occurred only when slow warming (approximately 2 degrees C/min) was continued to -60 degrees C or above. Parallel cryomicroscopical observations indicated that embryos became dehydrated during slow cooling to -30 degrees C and did not freeze intracellularly during subsequent rapid cooling (approximately 250 degrees C/min) to -150 degrees C. During slow warming (2 degrees C/min), however, intracellular ice appeared at a temperature between -70 and -65 degrees C and melted when warming was continued to -30 degrees C. Intracellular freezing was not observed during rapid warming (250 degrees C/min) or during slow warming when slow cooling had been continued to -65 degrees C. These results indicate that glycerol provides superior or equal protection when compared to dimethyl sulphoxide against the deleterious effects of freezing and thawing.

Animals↗