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Biomedical subjects

J Tesarík

Publications and source records attributed to J Tesarík.

At least 19 recordsLinked to original sources
PubMed1991

Proteins and glycosaminoglycans in the intercellular matrix of the human cumulus-oophorus and their effect on conversion of proacrosin to acrosin.

Human cumuli-oophori were cultured in vitro in the presence of radioactive protein and polysaccharide precursors. The time course of the cumulus cell secretion was traced by histoautoradiography. Matrix solubilization, and sodium dodecyl sulphate polyacrylamide gel electrophoresis and high-performance liquid chromatography showed that proteoglycan (Mr greater than 1,700,000) was the main cumulus cell product that was prevailingly deposited in the cumulus intercellular matrix and partly released into the culture medium. It was capable of accelerating the conversion of proacrosin to acrosin and this activity was abolished by enzymatic removal of chondroitin sulphate, the predominant glycosaminoglycan of this proteoglycan fraction. None of the other fractions, including a proteoglycan of Mr 80,000-90,000, containing heparan sulphate, accelerated the conversion of proacrosin to acrosin under the conditions used. The results suggest that chondroitin sulphate is the active component of the high-Mr proacrosin activator of the human cumulus-oophorus.

Acrosin↗
PubMed1990

Effect of the human cumulus oophorus on movement characteristics of human capacitated spermatozoa.

The effect of human cumulus oophorus on movement characteristics of human spermatozoa previously incubated in vitro under capacitating conditions was studied using automated digital image analysis. When spermatozoa were incubated for a short time with whole cumuli, most of those that penetrated the cumulus intercellular matrix were characterized by a linear movement with small amplitudes of lateral head displacement, but with elevated values of beat cross frequency. Short (5 min) incubation with solubilized cumulus intercellular matrix of spermatozoa preincubated in capacitating conditions (6 h) significantly reduced the percentage of spermatozoa showing the 'hyperactivated' type of motility characterized by high curvilinear velocity, low progressive velocity and elevated values of lateral head displacement. Moreover, a subpopulation of spermatozoa with very high values of progressive velocity and beat cross frequency and with reduced amplitudes of lateral head displacement appeared in these conditions. This cumulus-related motility pattern was not seen in fresh spermatozoa or in those incubated in the absence of cumulus material. Changes in the sperm movement characteristics similar to those observed in the presence of the solubilized cumulus matrix could also be induced by some of its h.p.l.c. fractions. These results show that the intercellular matrix of the human cumulus oophorus exerts a specific effect on human sperm motility, probably acting preferentially on the 'hyperactivated' sperm subpopulation.

Cells, Cultured↗
PubMed1990

[Gamete and embryo transfer in conjunction with microsurgical treatment of sterility].

The authors evaluate the results of the programme of transfer of gametes into the oviduct or of embryos into the uterus in conjunction with microsurgery of sterile women. During the period between August 1981 and December 1988 a total of 211 microsurgical operations were made in stimulated cycles. The ovaries were stimulated with clomiphene citrate or in combination with human menopausal gonadotropin. The operation was made 36 hours after administration of human choriogonadotropic hormone. In 146 women at least one oocyte was obtained. A total of 72 gametotransfers into the oviduct were made and in eight, i. e. 11.1%; pregnancy was achieved. Of 43 embryotransfers five pregnancies were achieved, i. e. 11.6%. A total of 13 pregnancies were achieved with four spontaneous deliveries, seven miscarriages and two extrauterine pregnancies. The combination of selected cases of microsurgery of sterility with the IVF programme increases the rate of successful operations without a further burden for the patient, and it extends the possibilities of sterility treatment.

Adult↗
PubMed1989

Involvement of oocyte-coded message in cell differentiation control of early human embryos.

Considerable evidence indicates that the first phenotypical diversification of embryonic cells during mammalian preimplantation development is achieved in two successive steps: (i) generation of cell asymmetry and (ii) unequal cell division. This paper shows that ultrastructural signs of blastomere surface regionalization in human preimplantation embryos are evident as early as the 2-cell stage when modifications of the plasma membrane (loss of microvilli and endocytotic activity, formation of cell junctions) are induced in places of blastomere contact. The capacity of the plasma membrane to undergo these cell-contact-dependent changes precedes any detectable activity of the embryonic genome. The area of the modified plasma membrane shows a continuous increase during the first three cleavage stages. The progression of these membrane modifications is the same in embryos that have properly enhanced their transcriptional activity at the 8-cell stage and in those that have not. In spite of the failure of this early-cleavage-progressed-cleavage transition of gene activity, the formation of zonula adherens and gap junctions goes on apparently normally in the respective embryos and morphologically distinct inner cell mass and trophectoderm cell lineages are subsequently segregated in 16-cell morulae. However, tight junctions do not develop under these conditions. The occurrence of the progressed-cleavage pattern of gene activity in the majority of embryonic cells is a necessary prerequisite for the appearance of the blastocyst cavity. Thus, oocyte-coded message is apparently involved in the control of relatively late stages of human preimplantation development including the differentiation of the first two embryonic tissues, but the embryonic genome is required for the full achievement of this early differentiative event.

Blastomeres↗
PubMed1989

Nucleic acid synthesis and development of human male pronucleus.

Polyspermically penetrated human zona-free eggs prepared from oocytes that had failed to be fertilized in an in-vitro fertilization programme were used. The pronuclear synthetic activity was evaluated by high-resolution autoradiography and correlated with the development of pronuclear structure. Incorporation of [3H]-thymidine, signalling the occurrence of a DNA synthetic phase, was only detected in structurally fully developed pronuclei previously shown to appear no sooner than 12 h after gamete union. However, [3H]adenosine was incorporated into very early pronuclei which had not yet completed the development of their nuclear envelopes and which first appeared about 4 h after sperm-egg fusion. In the absence of DNA synthesis (shown by the lack of thymidine incorporation), this early adenosine incorporation apparently reflects an early pronuclear RNA synthesis. Taken together, these results indicate that nucleic acid synthesis in human male pronuclei is tightly bound to the development of a corresponding pronuclear structure and that DNA synthesis, beginning about 12 h after fertilization, is preceded by a slight but evident RNA synthesis taking place during an early stage of human male pronuclear formation.

Adenosine↗
PubMed1989

Immunoinhibition of human fertilization in vitro by antibodies to the cumulus oophorus intercellular matrix.

Rabbit polyvalent antiserum raised against the solubilized cumulus matrix was a powerful inhibitor of human fertilization in vitro, affecting sperm-zona pellucida interaction. Both sperm binding to, and penetration of, the zona pellucida were severely impaired by the anti-cumulus matrix antiserum, whereas no effects of this antiserum on cumulus matrix solubilization or penetration of zona-free human eggs were evident. Moreover, the anti-cumulus antiserum partly neutralized the acrosome reaction-inducing activity of the cumulus matrix. These results warrant further research into the functional specificity of different cumulus matrix components and into the effects of the respective antibodies on reproductive function as a possible lead to a new approach to contraceptive vaccine development.

Contraception↗
PubMed1989

[Initial experience with cryopreservation of human embryos].

We present our first experience with human embryo cryopreservation. In our hands the best results were obtained with cryopreservation of pronuclear-staged embryos using propanediol as cryoprotectant. In this group 3 embryos out of 4 continued their development after thawing. The advantages of embryo cryopreservation in IVF programs are discussed.

Cryopreservation↗
PubMed1989

[Developmental capacity of human embryos after cryopreservation in the unicellular zygote stage].

This study deals with the developmental competence of human embryos after cryopreservation at the one-cell stage using propanediol as cryoprotectant. From 11 frozen zygotes, nine underwent cleavage after thawing. The occurrence of multinuclear blastomeres was the most frequent abnormality which, however, can often be observed in fresh embryos as well. The results of an ultrastructural analysis of the developing frozen-thawed embryos, with special attention to markers of embryonic genome expression, did not show any noticeable impairment of the developmental competence of these embryos as compared with parameters previously described for unfrozen embryos. The findings are discussed with particular reference to current freezing policies in human in-vitro fertilization programmes.

Cryopreservation↗
PubMed1989

[Clinical approaches and factors affecting the results of fertilization in vitro in 1987].

In 1987 at the First Gynaecological and Obstetric Clinic in Brno a total of 314 stimulated cycle were monitored as part of the IVF and ET programme. 206 cycles (65.6%) were stimulated by means of clomiphene citrate and 108 cycles (34.4%) by a combination of clomiphene with hMG. Before aspiration 76 cycles (24.2%) were abolished, incl. 60 cycles because of inadequate stimulation. Aspiration of follicular fluid was made in 147 women by the laparoscopic route, in 91 women by transvaginal aspiration, using a vaginal ultrasonic probe. Of 238 aspirations of follicular fluid in 190 women at least one oocyte was obtained, a total of 412 oocytes, i. e. 1.73 +/- 1.4 oocyte per aspiration. A total of 146 oocytes were fertilized, i. e. 35.4% and an embryo transfer was made in 98 instances. In 1987 10 pregnancies were achieved, i. e. 10.2% pregnancies per one embryo transfer. Two preclinical abortions, four clinical abortions and four pregnancies were involved which terminated by the delivery of five healthy infants. The most important factor influencing the number of pregnancies after IVF and ET is the number of transferred embryos. 5.2%, 14.7% and 25% pregnancies per one to three transferred embryos were achieved. In order to make the results of different IVF and ET centres comparable, the authors recommend to classify the achieved pregnancies as the ratio of pregnancies per number of transferred embryos, stating the ratio of different groups. For the lay public the results per aspiration of follicular fluid should be published.

Female↗
PubMed1989

[A simple microphotographic method for the evaluation of sperm motility].

A simple objective method for examination of sperm quality, both for practical and research purposes, is described. The results obtained show that the evaluation of samples must be performed by 15 minutes after the removal of the spermatozoa from the culture system and by 5 minutes after the placement on the microscope slide, in order to avoid the influence of external conditions on sperm motility. From the comparison of parameters examined (percentage of sperm motility, mean velocity, lateral head displacement, number of waves per second, distribution in individual speed intervals) it follows that media used for sperm incubation (B2 and F 10) do not affect negatively sperm motility and may be exchanged with each other if necessary. The results contribute to the improvement of diagnostic and treatment of andrological disturbances. The study will be used in our programme of treatment of infertile couples.

Humans↗
PubMed1988

Developmental control of human preimplantation embryos: a comparative approach.

The period for which oocyte-derived factors are engaged in the control of human embryonic development involves at least the first four cell cycles after fertilization. The maternal-embryonic transition in humans 8- to 16-cell embryos is a relatively vulnerable process, the failure of which entails developmental arrest of the given blastomere. The very early cellular differentiative events in human embryos, including blastomere surface polarization and segregation of the inner cell mass and trophectoderm cell lineages, appear to be dependent largely on the maternal genetic program. However, the embryonic genome is required for the formation of the blastocyst cavity, which is necessary to allow further differentiation of the first two embryonic tissues. Blastomeres with major developmental defects are removed by fragmentation and their loss is compensated by proliferation of remaining normal blastomeres. This mechanism is also mainly responsible for the regulation of ploidy through elimination of aneuploid blastomeres. The data presented suggest that embryos of individual mammalian species may differ in the timing of relevant developmental changes at the cellular and molecular levels. This should be taken into account when findings obtained on embryos of one species are used to anticipate the behavior of embryos of another species under identical conditions.

Blastocyst↗
PubMed1988

Early morphological signs of embryonic genome expression in human preimplantation development as revealed by quantitative electron microscopy.

A quantitative electron microscopic analysis of human preimplantation embryos in conjunction with [3H]uridine labeling and light microscopic autoradiography revealed significant differences in the fractional volume of some cell organelles between the blastomeres of eight-cell embryos with fully activated extranucleolar and nucleolar transcription and those showing low extranucleolar and no nucleolar RNA synthesis, a pattern typical of four-cell human embryos. The latter type of blastomeres in eight-cell embryos did not show any significant quantitative cytological difference when compared to blastomeres of four-cell embryos. The phenotypical changes accompanying the overall enhancement of the embryonic transcriptional activity (increase in tubules/vesicles ratio and lysosomes, decrease in Golgi apparatus) were due to repartition of intracellular membranes amongst different types of organelles rather than to a noticeable change in the existing equilibrium between total membrane production and degradation.

Blastomeres↗
PubMed1988

Subcellular immunochemical localization of acrosin in human spermatozoa during the acrosome reaction and zona pellucida penetration.

The changes in acrosin immunoreactivity in human spermatozoa undergoing spontaneous or chemically induced acrosome reactions were studied by electron microscopic immunocytochemistry with an acrosin-specific monoclonal antibody. Migration of limited amounts of acrosin to the sperm surface was the earliest event characterizing the beginning of the acrosome reaction. The acrosome of such spermatozoa remained morphologically intact, swelled, or showed intraacrosomal vesiculation without any disruption of the plasma and acrosomal membrane integrity. Massive release of acrosin coincided with the fusion of the plasma and outer acrosomal membranes. However, even fully acrosome-reacted spermatozoa always retained some acrosin on the exposed inner acrosomal membrane and in the equatorial segment of the acrosome. This residual acrosin was also detected on spermatozoa within the zona pellucida of human oocytes inseminated in vitro, while the previously released bulk of acrosin remained attached to the surface of the zona pellucida at the site of sperm entry. These findings are compatible with multiple functions of acrosin in human sperm-egg interaction, including sperm-zona pellucida binding, dispersal of acrosomal contents, and facilitation of zona pellucida penetration.

Acrosin↗