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E S Critser

Publications and source records attributed to E S Critser.

At least 37 records · Page 2Linked to original sources
PubMed1993

Evaluation of mouse sperm acrosomal status and viability by flow cytometry.

A procedure was developed to evaluate mouse sperm acrosomal status and viability simultaneously utilizing flow cytometry. Four fluorescein isothiocyanate (FITC)-conjugated lectins, peanut agglutinin (PNA), concanavalin agglutinin (ConA), Pisum sativum agglutinin (PSA), and soybean agglutinin (SBA), were investigated, with PNA providing the greatest sensitivity and specificity in distinguishing acrosome-present and acrosome-absent mouse spermatozoa. To expose lectin binding sites, digitonin (20 microM at room temperature for 10 min) was used to permeabilize sperm plasma membranes. Sperm cell viability was determined by Hoechst 33258-(H258) exclusion. To prevent permeabilized cells from staining with H258, salmon sperm DNA (SS-DNA) was applied to bind excess dye in the solutions after supravital staining. Calcium ionophore (A23187; 5 or 20 microM) was used to induce acrosome reactions. The results of flow cytometric analyses were compared with epifluorescence microscopic observation and were highly correlated (r = 0.999; P < 0.001). The method developed provides an objective and efficient procedure to estimate simultaneously both acrosomal status and viability of mouse spermatozoa.

Acrosome↗
PubMed1993

Assessment of the acrosomal status and viability of human spermatozoa simultaneously using flow cytometry.

Acrosomal status and viability were evaluated simultaneously on human spermatozoa using flow cytometry. Samples were divided into three aliquots and randomly assigned to one of three treatments: (i) cryopreservation; (ii) 10 microM calcium ionophore [A23187 in dimethylsulphoxide (DMSO)] or (iii) DMSO alone (control). Acrosomal status was evaluated using monoclonal antibodies recognizing MH61 and CD46, respectively. Fluorescein-conjugated goat anti-mouse immunoglobulin (IgG) was used as a second antibody. Sperm viability was assessed using Hoechst 33258 (H258) exclusion. The following factors were analysed: (i) the specificity of the monoclonal antibodies for the human acrosome; (ii) the relative effectiveness of flow cytometry and direct fluorescent microscopy scoring and (iii) the acrosomal status and viability of the control, ionophore-treated, and cryopreserved spermatozoa. Across all treatments, the MH61 and CD46 monoclonal antibodies resulted in acrosomal status values (acrosome-reacted/viable spermatozoa) which were not significantly different (P > 0.05): control, 1.0 +/- 0.3% and 1.5 +/- 0.6% (mean +/- SEM); A23187, 42.8 +/- 3.5% and 38.1 +/- 3.5%; cryopreserved, 8.2 +/- 2.0% and 9.9 +/- 1.3%; respectively. However, acrosomal status among treatments differed significantly (P < 0.01). Flow cytometric and direct fluorescent microscopy assessments were significantly correlated (r2 = 0.96, P < 0.01). These results indicate that flow cytometry, using an acrosome-specific monoclonal antibody and a supravital dye, provides an objective and efficient method to evaluate human sperm acrosomal and viability status simultaneously.

Acrosome↗
PubMed1992

Preimplantation genetics. An overview.

Advances in methods used to detect specific genes or gene products have contributed to the development of methods to identify genetic disorders in preimplantation embryos. A variety of strategies have been developed, including polar body biopsy, removal of cells from multicell stage embryos, and biopsy of the polar trophectoderm from expanded blastocysts. These embryos are derived primarily from oocyte retrievals and in vitro fertilization procedures, although blastocysts could be obtained by uterine lavage. A number of animal models have been evaluated that demonstrate the feasibility of such techniques in the diagnosis of genetic disease. Clinical trials are under way in a number of clinical centers and current outcomes with human embryos are cited.

Biopsy↗
PubMed1991

Pregnancy rates after peritoneal ovum-sperm transfer.

We present the technique of peritoneal ovum-sperm transfer as an option for treatment in couples with unexplained infertility factors. In 1989 we reported the first successful pregnancy, in the United States, after transferring sperm and oocyte into the peritoneal cavity. We now report the results of a prospective study of this procedure. Twelve women with unexplained infertility underwent 23 cycles of peritoneal ovum-sperm transfer. Ovulation stimulation was achieved with human menopausal gonadotropin. Ultrasonographically directed oocyte recovery was performed by the transvaginal route with the patient under local anesthesia and sedation. After oocyte recovery, 4.5 +/- 0.4 (mean +/- SE) oocytes and 13.3 +/- 1.0 (mean +/- SE) x 10(6) motile spermatozoa were transferred into the pouch of Douglas. Six clinical pregnancies occurred in 23 stimulated cycles for a pregnancy rate of 26% per cycle. This value compares with the overall pregnancy rates of 16% for in vitro fertilization and 27% for gamete intrafallopian transfer reported by the In Vitro Fertilization Registry. Thus these preliminary data suggest that peritoneal ovum-sperm transfer is at least as successful as in vitro fertilization and gamete intrafallopian transfer. Advantages of peritoneal ovum-sperm transfer over gamete intrafallopian transfer include its being an office nonsurgical procedure not necessitating a general anesthetic and decreased cost. Therefore peritoneal ovum-sperm transfer is a reasonable first approach in couples with unexplained infertility.

Adult↗
PubMed1990

Cloning of a gap junctional protein from vascular smooth muscle and expression in two-cell mouse embryos.

Gap junctional proteins (connexins) form aqueous channels that enable direct cell-cell transfer of ions and small molecules. The distribution and conductance of gap junction channels in cardiac muscle determine the pattern and synchrony of cellular activation. However, the capacity for smooth muscle to restrict contractile events temporally and spatially suggests that cell-cell coupling or its regulation may be decidedly different in this tissue. We isolated a cDNA from vascular smooth muscle which encodes a connexin (Mr 43,187) structurally homologous to cardiac connexin43. Vascular smooth muscle connexin43 mRNA was expressed prominently in smooth muscle tissues, cultured vascular myocytes, and arterial endothelial cells. A model for functional expression of connexins was developed in two-cell B6D2 mouse embryos. Microinjection of in vitro transcribed vascular smooth muscle connexin43 mRNA was shown to be sufficient to induce intercellular coupling in previously uncoupled blastomeres. Through the construction of two deletion mutants of connexin43, we also show that the formation of cell-to-cell connections does not depend upon a predicted cytoplasmic region within 98 residues of the carboxyl terminus. Finally, the identification of connexin43 in smooth muscle and endothelial cells provides supporting evidence for the existence of heterocellular coupling between cells of the vascular intima.

Amino Acid Sequence↗
PubMed1989

Pregnancy resulting from peritoneal ovum sperm transfer procedure.

This is the first reported transvaginal ultrasound-guided POST pregnancy in the United States. Advantages over the GIFT procedure include it being an office procedure done under local anesthesia and IV sedation, and decreased cost. Larger series are needed to compare pregnancy rates.

Adult↗
PubMed1989

An evaluation of the accuracy of screening antisperm antibodies using the combined GAM immunobead.

A simplified method of screening for antisperm antibodies has been previously described using rabbit antihuman immunoglobulin immunobeads (GAM beads). These reports have indicated a high correlation between the GAM bead and maximal individual isotype binding. However, preliminary data in our laboratory (using a 14% cut-off criterion) indicated a high frequency of samples with positive GAM bead, but negative individual isotype results. This study was conducted to evaluate more critically the use of the GAM bead for initial antisperm antibody screening. Immunobead binding tests were performed on 98 undiluted sera. The maximal binding of the individual isotype beads (IgG, IgA, or IgM) and the GAM beads were significantly correlated (r = 0.94, P = 0.0001). However, when results were categorized as positive or negative, there was a significantly lower frequency (P less than 0.05) of positive samples using the individual isotype (46.9%) than using the GAM approach (58.2%). These data support the hypothesis that, based on continuous percent binding, the GAM bead method produces results similar to individual isotype testing. However, when data are interpreted categorically, the results may differ significantly.

Acrylic Resins↗
PubMed1988

Lower sodium lactate in Whitten's medium improves in vitro developmental capacity of one-cell mouse embryos.

A modification of Whitten's medium, involving a reduced content of Na-lactate syrup (0.2 ml/100 ml; 11.65 mM) and osmolarity (251 mOsm), was compared with normal Whitten's medium (0.37 ml/100 ml; 21.6 mM) for ability to support mouse embryonic development in vitro from one-cell to the blastocyst stage. In a pilot study utilizing 10 ICR donor female mice, in vitro developmental capacity (IVDC; percentage of fertilized one-cell embryos developing to blastocysts in vitro per female donor) was significantly enhanced by the modified medium (68.0 versus 24.0%; P<0.001). In the main study, utilizing 134 ICR and 17 ICR x C57BL/6J F(1) donor females, the modified medium supported increased IVDC for both ICR (67.9 versus 51.1%; P<0.001) and F(1) females (98.5 versus 89.4%; P<0.05). A large degree of among donor-female variation in IVDC was observed for both media in the ICR stock (SD = 30.0). The beneficial role of the reduction of Na-lactate in Whitten's medium may be related to an improved provision of energy requirements for first cleavage and/or a more suitable osmolarity for development.

Journal Article↗
PubMed1987

Development potential of bovine oocytes matured in vitro or in vivo.

Bovine oocytes matured in vivo or in vitro were evaluated after sperm-oocyte incubation for frequency of sperm penetration, frequency of male pronuclei formation, and embryonic development. The frequency of sperm penetration was not different for in vitro matured oocytes (216/295, 73%) vs. in vivo matured oocytes (119/176, 70%). However, formation of male pronuclei was reduced (p less than 0.05) for oocytes matured in vitro (149/216, 69%) vs. in vivo (104/119, 88%). Early embryonic development was evaluated 48 h after the onset of sperm-egg incubations. In vitro matured and fertilized oocytes failed to develop to the 2-cell stage (3/88, 3%), whereas oocytes matured in vivo showed normal development (23/56, 40%) to the 2- and 4-cell stage. Development to the blastocyst stage was evaluated after 5 days in ovine oviducts (in vivo). Morulae and blastocysts were obtained only after in vitro fertilization from oocytes that were in vivo-matured (recovered from oviduct, 14/56, 25%; recovered from follicle, 36/80, 45%). Oocytes that were matured in vitro and fertilized in vitro failed to develop to morulae (0/33) in vivo.

Animals↗
PubMed1986

Bovine in vitro fertilization with frozen-thawed semen.

A procedure to obtain high and repeatable fertilization frequencies for bovine in vitro fertilization (IVF) with frozen-thawed sperm was developed. IVF frequency of in vitro matured oocytes was increased by a swimup sperm separation procedure (P=0.01) or treatment of sperm with the glycosaminoglycan heparin (P=0.0001), but the two factors did not interact (P=0.23). Heparin was the most important factor in increasing IVF frequencies. The fertilization frequency was not affected by the batch of oocytes used (P=0.38), but bull effects were present (P<0.05). Within a bull, the IVF system was highly repeatable and varied between trials no more than +/- 12% in fertilization frequency with an overall fertilization frequency of 299 379 (79%) on four trials over four bulls. In vivo matured oocytes fertilized in vitro were transferred to ewe or heifer oviducts. Morulae or blastocysts were recovered from ewes after four to five days, while conceptuses were present in the bovine after 25 days (diagnosed by ultrasound). Embryonic development from the IVF system either pre- or postimplantation was normal.

Journal Article↗
PubMed1986

Nuclear transplantation in mouse embryos: assessment of recipient cell stage.

Enucleated zygotes were compared with enucleated two-cell embryos as recipients for donor nuclei from eight-cell embryos. Only one or two cleavage divisions were observed when eight-cell nuclei were transplanted to enucleated zygotes. Development of enucleated two-cell embryos containing a transplanted eight-cell nucleus was appreciably better with 51% (45/89) of the embryos forming blastocysts in vitro and 42% (25/60) initiating implantation. Of these, eleven implantation sites on Day 10 of gestation were examined histologically and two contained normally developing embryos. No development was observed beyond Day 12 of gestation. These observations indicate that a major transition occurs between the zygote and two-cell stage that results in the two-cell recipient being more compatible with the eight-cell nucleus than with the zygote.

Animals↗
PubMed1986

Effects of fetal calf serum and bovine serum albumin on in vitro maturation and fertilization of bovine and hamster cumulus-oocyte complexes.

Bovine serum albumin (BSA) and fetal calf serum (FCS) were evaluated as protein supplements for in vitro maturation and fertilization of oocytes from cows and hamsters. BSA and low doses of FCS (0.1 or 1.0%) did not support viability or maturation of the cumulus-oocyte complex as well as higher doses of FCS (5, 10, or 20%) for either species. BSA failed to support cumulus expansion for bovine or hamster cumulus-oocyte complexes. All doses of FCS examined supported cumulus expansion in bovine cumulus-oocyte complexes, whereas the hamster complexes required at least 1.0% FCS to induce cumulus expansion. The addition of a serum filtrate, Solcoseryl, with BSA improved viability of the cumulus in the bovine but did not support cumulus expansion or completion of Meiosis I in bovine complexes. In vitro fertilization could be accomplished in media containing FCS by increasing the heparin concentration in the bovine system or reducing FCS for the hamster system. Polyspermy was increased when FCS was the protein supplement. It is not known whether this is an interaction of FCS with the sperm or oocyte. In conclusion, FCS was found necessary for follicle-stimulating-hormone (FSH)-induced cumulus expansion. It also improved cumulus cell viability and completion of the first meiotic division in complexes of both species compared with BSA.

Animals↗
PubMed1986

Use of a fluorescent stain for visualization of nuclear material in living oocytes and early embryos.

Hoechst dyes 33342 and 33258 were used to visualize pronuclei and nuclei of early preimplantation embryos. Murine one-cell zygotes exposed to dye stained rapidly over a range of concentrations (0, 0.02, 0.04, 0.1 or 0.2 micrograms/50 microliter of media). Development to morula and blastocyst in vitro was reduced (39/70, 56%; p less than 0.05) compared to controls (44/57, 77%) but not completely blocked. Porcine and bovine zygotes and embryos could also be stained but required incubation times up to 4 hr. Porcine embryos exposed to Hoechst 33342 had limited (p less than 0.01) in vitro development (29/74, 39%) compared to unstained controls (49/64, 76%). Hoechst dyes stain embryos from different species but suitably adjusted incubation times are required. Limited preimplantation development in vitro may be expected following staining and exposure to ultraviolet light.

Animals↗
PubMed1984

Developmental potential of isolated blastomeres from early murine embryos.

Experiments were designed to evaluate the effect of blastomere separation on blastocoele formation and development of viable fetuses. Two-cell and four-cell murine embryos were dissociated into individual blastomeres and cultured to the blastocyst stage. For embryos of both stages, zona removal and blastomere separation reduced (P<0.05) the number of viable embryos at the onset of culture and reduced (P<0.01) the frequency of continuation of development of blastomeres to the blastocyst stage. Attempts to repeatedly split two-cell stage embryos decreased in vitro development to blastocysts. The number of cells in two-cell embryos that were cultured to blastocyst was not different for control (64.8 +/- 11.5) or for two-cell embryos cultured without the zona pellucida (60.9 +/- 10.1) but was reduced (P<0.01) for one-half embryos that were cultured to blastocysts (35.6 +/- 10.6). The cell number of blastocysts obtained from dissociated four-cell (1/4) embryos (17.4 +/- 1.4) was similarly reduced (P<0.01). In vivo development was assessed after cultured embryos were transferred to the uteri of day 3 pseudopregnant females. Zona free intact embryos (2/36, 6%) and zona free half embryos (7/36; 19%) developed less frequently (P<0.05) than intact controls (45/100). Noncultured morula briefly exposed to pronase to thin the zona had similar impaired development. Embryos with thinned zona or no zona developed less frequently (21/82, 2/72 respectively, P<0.05) than nonpronase-treated controls (50/83).

Journal Article↗
PubMed1984

The effect of semen extension, cAMP and caffeine on in vitro fertilization of bovine oocytes.

A previously reported in vitro system that used epididymal spermatozoa for fertilizing bovine follicular oocytes (1) has been expanded to include ejaculated semen as the sperm source. Frequency of fertilization was higher when semen was extended 1:1 prior to transport to the laboratory rather than transport as neat semen. Pretreatment of spermatozoa with cAMP, caffeine or both prior to insemination of oocytes did not increase frequency of either acrosome reactions or fertilization after sperm/oocyte incubation.

Journal Article↗
PubMed1982

Control of luteal function during pregnancy: antiluteolytic and luteotropic properties of the developing mouse conceptus.

Eight experiments were conducted to examine the influence of the conceptus on luteal function in mice. In uterine intact pseudopregnant mice, exogenous treatment with placental extracts or pregnant mouse plasma from Day 8 or Day 10 of gestation did not prolong the life span of the corpora lutea (CL). The interestrous interval (IEI) of hysterectomized pseudopregnant mice was extended by treatment with Day 10 placental extract and was accompanied by elevated plasma progesterone, consistent with the luteotropic nature of the Day 10 conceptus. The IEI of uterine intact pseudopregnant mice was prolonged by the presence of ectopically developing blastocysts and was further extended by a treatment with Day 10 placental extracts but not by treatment with Day 8 placental extracts. Although the ectopic blastocyst delayed the effect of the uterine luteolytic mechanism, there was no indication of luteotropic activity: the ectopic blastocysts were unable to activate the CL of the estrous cycle. In addition, plasma progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were measured in pseudopregnant, hysterectomized pseudopregnant and pregnant mice on Day 2 through 13 post-mating. The results of these experiments suggest a two-step mechanism in prolonging luteal function during pregnancy which involves two different substances. This mechanism involves an initial signal from the conceptus which blocks the uterine luteolytic mechanism and a subsequent luteotropic stimulus from the Day 10 conceptus which extends luteal life span to approximately the length of gestation.

Animals↗
PubMed1982

Plasma concentrations of progesterone and 13,14-dihydro-15-keto prostaglandin F-2 alpha in pregnant, pseudopregnant and hysterectomized pseudopregnant mice.

Hysterectomized pseudopregnant mice had plasma progesterone concentrations on Days 6, 8, 10 or 12 after mating that were greater (P less than 0.05) than those of intact pseudopregnant mice and lower (P less than 0.01) than those of pregnant mice. Concentrations of 13,14-dihydro-15-keto-prostaglandin F-2 alpha on Days 6, 7, 8, 9 or 10 after mating were lower (P less than 0.05) in pregnant and higher (P less than 0.01) in intact pseudopregnant mice than in hysterectomized pseudopregnant mice. The results support the conclusion that there are uterine and extra-uterine luteolytic mechanisms which are mediated by prostaglandin and are perhaps functional by Day 6 of pregnancy.

Animals↗