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M T Zenzes

Publications and source records attributed to M T Zenzes.

At least 37 records · Page 2Linked to original sources
PubMed1986

[Clinical aspects of 7 pregnancies following in vitro fertilization and embryo transfer (IVF/ET)].

Between September 1, 1983 and June 15, 1984 69 patients were treated by in-vitro fertilization as part of a clinical research project. The scientific questions were aimed at optimizing the principal methodological aspects of the new technique. One hundred and sixty-nine follicle punctures were performed under laparoscopic or ultrasonographic control. A total of 207 preovulatory oocytes were obtained, 57 of which were transferred to the uterus as cleaving embryos following in-vitro fertilization. Seven clinical pregnancies were diagnosed. Two resulted in spontaneous abortion in the fifth and sixth week of gestation, the remaining five as three single and two twin births. The infrastructure of reproduction medicine has been broadened successfully within a short time. Considering the results of current clinical and experimental research, the efficiency of the methods used is likely to be improved.

Abortion, Spontaneous↗
PubMed1986

Time course of human sperm transformation in the cytoplasm of zona-free hamster ova.

The time required for nuclear transformation of human spermatozoa in the cytoplasm of zona-free hamster ova was determined using semen samples from four individuals. Zona-free ova were incubated with capacitated spermatozoa for either 3 h or for 4-8 h. After the first hour of insemination, up to 85 ova were fixed at 1-h intervals. Assessments of sperm transformation were carried out on Giemsa-stained preparations of ova. Considerable variation between individuals was found in the maximal time of sperm decondensation, ranging from 2 to 7 h. Decondensing sperm heads developed into pronuclei within 3-5 h. At and subsequent to pronuclear formation, the incidence of decondensing sperm heads was considerably reduced in both insemination times. This variability in sperm transformation is relevant in clinical evaluations of the functional capacity of spermatozoa.

Adult↗
PubMed1985

Cytologic investigation of human in vitro fertilization failures.

A cytogenetic study of unsuccessfully fertilized oocytes was done for information on the frequency and type of chromosomal abnormalities leading to preimplantation loss. Of 72 oocytes, 44 were assessed as mature, 19 as intermediate, and 9 as immature. The mean fertilization rate was 68%. This rate was significantly lower in immature oocytes than in mature ones (22% versus 79%). Immature oocytes completed maturation in vitro up to metaphase II of meiosis. Intermediate oocytes became fertilizable, however, a significant proportion showed morphologic abnormalities after fertilization. Thus, eggs with three pronuclei were hypotriploid or had three prophasic chromosome sets, together with polyspermy and with first polar body chromosomes. Eggs with developmental arrest showed marked asynchrony in pronuclear morphogenesis. One had a chromosome complement of 24,XX. It is concluded that insemination prior to completion of maturation leads to abnormal development.

Adult↗
PubMed1984

Variability in serologically detected male antigen titer and some resulting problems: a critical review.

Seroologically detected male antigen" (also called H-Y antigen) was first described in normal male mammals but now appears to occur in normal female mammals as well. "Serologically detected male predominant" (SDMP) antigen is a more appropriate name since the titer in normal males usually exceeds that of normal females. As we show, in each sex there is a considerable inter-individual variability in SDMP antigen titer, and in moderate-to-large size samples the low end of the male range of titers usually coincides with the high end of the female range. Several major problems arise from failure to recognize and/or to deal adequately with this normal variation in SDMP antigen titer. The chief problem is that the "controls" used (often a single individual) may be inadequate and misleading, leading to unjustified designation of samples as "positive", "negative", or even "deviant" ("intermediate", "reduced") for SDMP antigen titer. Other problems include deficiencies in technique and lack of statistical control for test and sample variability. Adequate attention to these problems, especially to the normal variability in SDMP antigen titer, could reduce the contradictions and inconsistencies which have troubled this field.

Animals↗
PubMed1981

Cell reorganization in vitro of heterosexual gonadal cocultures.

Male and female gonadal cells of newborn rats were cocultured in varying proportions. As low a proportion as 20% of male cells essentially yielded tubular structures. At lower quotas of testicular cells, however, only follicular structures occurred. Mixed structures were not observed except one experiment (20% male cells). When ovarian cells were cocultivated with male nongonadal cells, no conversion occurred. It is assumed that H-Y antigen secreted by male gonadal cells is bound by the ovarian receptor sites and induces conversion into tubular structures. H-Y antigen integrated into the cell membrane of nongonadal male cells does not seem to be able to exert this morphogenetic effect.

Animals↗
PubMed1981

H-Y antigen negative germ cells in gonadal sex organization in vitro: a morphological study.

Dissociation-reorganization experiments were done with gonadal cells of newborn rats. Rotation cultures consisted of mixtures of somatic and germ cells of opposite sex. Somatic cells, ovarian or testicular, determined a female or male type respectively, of gonadal histomorphic organization. Germ cells did not affect the type of organization of somatic cells. Accordingly, suspensions containing somatic cells of one sex together with germ cells of both sexes, reorganized in rotation culture, into either a) follicles containing XX or XY germ cells, or b) tubules containing XX or XY or both types of germ cells. These results give morphological evidence for heterosexual germ-somatic cells interactions. Based on morphological and H-Y antigen studies, failure of germ cells to bind and express H-Y antigen is considered as a possible factor for this failure of germ cells to affect gonadal sex.

Cells, Cultured↗
PubMed1981

The capacity of ovarian cells of the postnatal rat to reorganize into histiotypic structures.

Cell-reorganization experiments in vitro were performed with dissociated rat ovaries at different ages of postnatal development, namely newborn, 8-10, 15-22, and 90-day-old. Ovarian cells consistently aggregated into follicularlike structures. Follicular organization ion vitro is comparable to the ovarian histology of the respective age. The histogenic properties conserved by ovarian cells are considered to be related with the morphogenetic processes steadily occurring in the ovary.

Animals↗
PubMed1981

The capacity of testicular cells of the postnatal rat to reorganize into histotypic structures.

Cell reorganization experiments in vitro were performed with dissociated rat testes at different ages of postnatal development namely, newborn, 8-10, 18-25, 35-40, and 90 days. Only newborn and juvenile rat testicular cells reassociated into testicular-like organization in rotation culture. Puberal and adult rat testicular cells show morphogenetic organization when they were deprived or germ cells by busulphan pretreatment. A factor present in testicular tissue of puberal and adult rats inhibits reorganization. The inhibitor is confined to the spermatic cell fraction in the testis.

Aging↗
PubMed1980

Inhibition of testicular organization in vitro by newborn rat ovarian cell supernatants.

Cell reorganization experiments performed with newborn rat gonadal single cell suspensions resulted in organ-like reorganization after 18 h of rotation culture. When, however, testicular cells were incubated in supernatants of newborn rat ovarian cells, testicular organization was suppressed and the architecture of the reorganized gonad was rather feminine. Supernatants of adult rat ovarian cells did not inhibit testicular organization. The possible mechanisms responsible for the failure of the function of H-Y antigen by the presence of ovarian cell supernatants of newborn rats are discussed.

Animals↗
PubMed1980

Mammalian cross-reactive H-Y antigen induces sex reversal in vitro in the avian testis.

Testes of either newborn rats or newly hatched chickens, dissociated into single cell suspensions, reorganize in vitro into their histotypic structures. In birds, the heterogametic female sex is H-Y antigen positive, and not the male as in mammals. Cocultivation of rat and chicken testicular cells results in the reorganization of an ovotestis. A similar result is obtained after cultivation of chicken testicular cells in the supernatant medium of cultured human male Burkitt lymphoma Daudi cells. Rat testicular Sertoli cells as well as Daudi cells are a source of H-Y antigen. The simultaneous application of H-Y antigen and anti-H-Y antiserum prevents ovotestis formation. It is concluded that H-Y antigen which is known to be testis-organizing in mammals, is the ovary-organizing factor in birds.

Animals↗
PubMed1979

Pattern of activity of nucleolus organizers during spermatogenesis in mammals as analyzed by silver-staining.

Silver-staining in the nuclei and chromosomes of spermatogenesis of four species of mammals (Man, Mus musculus, Rattus norvegicus, and Cavia cobaya) was investigated qualitatively and quantitatively. These species show a very similar pattern of activity of the nucleolus organizer regions (NORs) during the various stages of spermatogenesis. Silver precipitates are detectable in growing spermatogonia and up until the pachytene stage of meiotic prophase. During the meiotic metaphases I and II and during interkinesis silver-stainability disappears completely. A resumpton of silver-stainability occurs in round spermatids indicating a postmeiotic reactivation of NORs. This process does not persist beyond the early elongation phase. The quantitative determination of the silver-covered areas in relation to the total nuclear areas reveals minor differences between the species investigated with regard to the times and extents of maximum activation. The known localizations of the NORs in the karyotypes of the species investigated was confirmed using metaphase-preparations derived from somatic tissues.

Animals↗
PubMed1978

Studies on H-Y antigen in different cell fractions of the testis during pubescence: immature germ cells are H-Y antigen negative.

Various cell types of the rat testis during pubescence, including germ, Sertoli, and Leydig cells, were partially enriched. The fractions were tested for the presence, binding, and secretion of H-Y antigen. The main results are: Immature germ cells are H-Y antigen-negative until the late diploid stages, and late primary spermatocytes or spermatids become positive; the somatic cells of the gonad are positive at all ages examined (18 days old to adulthood). Secretion of H-Y antigen is restricted to the Sertoli cell fraction. Binding of externally supplied antigen takes place on Leydig cells; the Sertoli cell surface will be saturated because of active secretion; there is no binding to germ cells. Thus, immature germ cells seem to be the only H-Y antigen-negative cells of the male organism, and the Sertoli cells seem to be the only ones to secrete H-Y antigen.

Age Factors↗
PubMed1978

Appearance of hCG-receptor after conversion of newborn ovarian cells into testicular structures by H-Y antigen in vitro.

In a previous report (Zenzes et al., 1978b) it was shown that dissociated ovarian cells of newborn rats in vitro, if exposed to H-Y antigen, reorganize into testicular structures. The current study was designed to see whether this morphological conversion also results in a functional conversion. The LH/hCG receptor was used as a parameter characteristic for the newborn testis, but not for the newborn ovary. In the converted ovary, the LH/hCG receptor becomes detectable a few hours after onset of the culture and remains continuously present afterward. The appearance of this receptor may be due to a hormone-like action of H-Y antigen.

Animals↗
PubMed1978

The testis as a secretory organ for H-Y antigen.

After cultivation of dissociated rat testicular tissues, H-Y antigen is detectable in the medium; this is not the case if nongonadal male tissues are incubated. Release of H-Y antigen by testis cells is inhibited by the addition of cycloheximide. All tissues still type H-Y positive after culture. It is assumed that the testis actively secretes H-Y antigen. This assumption is supported by the finding that the amount of H-Y antigen in the epididymal fluid increases with the age of the animals.

Animals↗
PubMed1978

Organization in vitro of ovarian cells into testicular structures.

While it has been shown previously (Zenzes et al., 1978; Ohno et al., 1978) that when dissociated testicular cells are exposed to anti H-Y antiserum in vitro they are prevented from reorganizing into testicular structures, forming ovarian follicular structures instead, the most conclusive evidence for the action of H-Y antigen would be the conversion of ovarian cells into testicular organization. Testing for H-Y antigen of the medium collected from cultivated testicular cells revealed a positive reaction. Dissociated ovarian cells of newborn rats cultivated in this medium reorganize into testicular structures. It is concluded that H-Y antigen is responsible for this histomorphologic change.

Animals↗
PubMed1978

Binding studies of H-Y antigen in rat tissues: indications for a gonad-specific receptor.

The binding capacity for H-Y antigen was studied in various rat tissues of both sexes. In nongonadal tissues (liver, kidney, brain, epidermis) binding could not be demonstrated. In contrast, the gonads are able to bind exogenously supplied H-Y antigen. In the ovary, the binding capacity remains unchanged in newborn and adult animals, while in the testis, this capacity decreases with age. A receptor like that of a proteohormone is assumed to exist in the gonads but not in other tissues. In nongonadal tissues, H-Y antigen apparently is present only if the cell itself synthesizes the antigen. The H-Y antigen receptor of the gonads is not sex-specific. Thus, the primary sex differentiation depends on whether H-Y antigen is synthesized in the organism.

Animals↗
PubMed1978

Studies on the function of H-Y antigen: dissociation and reorganization experiments on rat gonadal tissue.

On circumstantial evidence, H-Y antigen is assumed to be responsible for the differentiation of the undetermined gonadal anlage into a testis. A direct approach to test the function of H-Y antigen is provided by Moscona-type experiments. Applying a modified technique of in vitro reassociation of cell suspensions, we obtained the following results: (1) dissociated newborn rat gonads, both testis and ovary, reorganize into histotypic structures; (2) under exposure to anti-H-Y antiserum, testicular cells reassociate into ovarian follicular-like organization; (3) anti-H-1 antiserum by itself does not prevent the testicular cells from forming tubular structures. It is concluded that H-Y antigen acts as a differentiation between preferably or exclusively on the cell elements participating in the formation of the seminiferous cords.

Animals↗