Human sperm--egg interactions and their disorders: implications in the management of infertility.

The present era of infertility management is characterized by an increasing interest in defects of sperm--egg interactions. When the spermatozoon meets the egg, it must first react with the enveloping coat which controls sperm access to the cell surface of the oocyte. Adequate sperm motility is a major condition for penetration through the egg investments.

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.

[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.

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.

[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.

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.

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.

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.

Activation of proacrosin by a locally produced component of human follicular fluid.

Components of human follicular fluid were separated on Sepharose 6B columns and the effects of different fractions on the conversion of pig proacrosin to acrosin were examined. A high-molecular-weight fraction (Mr greater than 3,000,000) of follicular fluid was a potent stimulator of this reaction. The proacrosin converting activity was absent in the corresponding fraction of blood serum.

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.

Zona pellucida resistance to sperm penetration before the completion of human oocyte maturation.

Human oocytes exposed to capacitated spermatozoa in vitro when at metaphase of the 1st meiotic division (metaphase I) were not penetrated, even though some subsequently progressed to metaphase of the 2nd meiotic division (metaphase II). When the non-penetrated oocytes that had reached metaphase II during the incubation with spermatozoa were freed from the zona pellucida and reinseminated, two or more pronuclei developed in most of them. By contrast, no penetration was observed when the oocytes were reinseminated in the zona-intact state.

The role of cumulus cell-secreted proteins in the development of human sperm fertilizing ability: implication in IVF.

Cumulus cells surrounding pre-ovulatory human oocytes were found to secrete a variety of proteins which became firmly associated with the cumulus intercellular material. Antibodies raised against human cumuli oophori completely blocked fertilization in vitro by impairing the sperm-zona pellucida interaction. A group of glycoproteins of high mol.

High-resolution autoradiographic localization of DNA-containing sites and RNA synthesis in developing nucleoli of human preimplantation embryos: a new concept of embryonic nucleologenesis.

Human embryos from the 2-cell to the morula stage, obtained by in vitro fertilization, were incubated with [3H]thymidine or [3H]uridine so as to achieve labelling of all replicating nuclear DNA and the newly synthesized RNA, respectively. The label was localized in different structural components of developing nucleoli using electron microscopic autoradiography. Careful study of the relationship between the structural pattern and nucleic acid distribution made it possible to define four stages of embryonic nucleologenesis.

Ultrastructural and autoradiographic observations on multinucleated blastomeres of human cleaving embryos obtained by in-vitro fertilization.

Human embryos from the 2-cell to the morula stage developing in vitro after monospermic fertilization were incubated with [3H]thymidine or [3H]uridine and those possessing multinucleated blastomeres were examined by conventional transmission electron microscopy and by light- and electron-microscope autoradiography. Labelled DNA was present in all nuclei showing normal ultrastructural appearance, in pseudonuclei lacking nucleoli and their precursors and often demonstrating an unusual chromatin organization, free in the cytoplasm in structures resembling aggregates of dense chromatin and in small cytoplasmic vesicles in the close vicinity of these aggregates. The labelling with [3H]thymidine was not detected in about 50% of the cytoplasmic chromatin aggregates, suggesting that this extranuclear DNA was no longer replicated.

Activation of nucleolar and extranucleolar RNA synthesis and changes in the ribosomal content of human embryos developing in vitro.

RNA synthetic activity of human 2-16-cell embryos developing in vitro was studied by [3H]uridine light-microscope autoradiography. Parallelly cut thin sections were examined in the electron microscope. The first extranucleolar RNA synthesis was detected in 4-cell embryos, but nucleoli were never labelled until the 3rd cleavage (6-8-cell embryos).

Distribution of sterols and anionic lipids in human sperm plasma membrane: effects of in vitro capacitation.

Filipin, a membrane beta-hydroxysterol probe, and polymyxin B (PXB), a probe for anionic lipids, were used to study human sperm plasma membrane (PM) with particular reference to changes induced by capacitation in vitro. In washed but noncapacitated spermatozoa the density of filipin/sterol complexes (FSC) was uniformly high in the PM overlying the acrosome, without any differences between its anterior and equatorial regions. The postacrosomal region was poor in FSC.