[Chromosome abnormalities in male infertility]. / Anomalies chromosomiques au cours des stérilités masculines.

On the basis of systematic cytogenetic studies carried out with men undergoing examination for infertility in the couple, it is now estimated that the incidence of chromosome anomalies is about 5 per cent. This rate is much higher than that observed in the general population (0.7 per cent). Anomalies in the sex chromosomes are the most frequently observed since they represent approximately 4 per cent of the cases, and the analysis of the various types of mutation shows a distinct predominance of the 47 chromosome composition, XXY, which is related to Klinefelter's syndrome. Autosome anomalies are also observed, notably Robertsonian and reciprocal translocations. They are more rare (about 1% of the cases), but the fact that they are linked with disturbances of spermatogenesis is an important element in understanding the control-mechanisms of this process. The occurrence in both man and animals of a non-random relationship between the forms of translocation and the X and Y chromosomes found in the seminal vesicle during the pachytene stage, suggests that this contact interferes with the normal process in which the X chromosome is inactivated. This interference could account for the observed deficits in spermatogenesis. The hypothesis is reinforced by the fact that female carriers of the same autosome translocations, whose two X chromosomes are normally active during the whole miotic prophase, have no fertility problems.

[Morphological aspect of embryos obtained after fertilization in vitro for male factor or ICSI]. / Aspect morphologique des embryons obtenus après une fécondation in vitro pour indication masculine ou ICSI.

OBJECTIVE: In order to study the eventual impact on fertilization and embryo characteristics of the microinjection procedure we compared the quality of the embryos obtained by ICSI with those of in vitro fertilization with male factors (MF IVF). MATERIAL AND METHODS: One hundred thirty-four cycles of IVF treatment (group 1) were selected with oligoasthenozoospermia according to WHO criteria with a total number of motile spermatozoa between 500,000 and 1 million. One thousand eighty-eight mature oocytes and 486 embryos were obtained. One hundred forty-three cycles of intracytoplasmic sperm injection (group 2) were performed in couples whose in vitro fertilization was imparticable because of extreme sperm impairment. One thousand one hundred forty-seven mature oocytes were injected and 626 embryos were obtained. RESULTS: In group 1, the pregnancy rate per embryo transfer and the implantation rate were respectively 22.7% and 12.3%. In group 2, the pregnancy rate per embryo transfer was 37.1% and the implantation rate was 17%. The statistical analysis of the embryos obtained in the two different groups did not demonstrate any difference in the distribution of the more regular and less fragmented embryos (group A) and those of the more irregular and fragmented embryos (group B). No statistical difference was demonstrated in the chronology of the division of these embryos (groups 1 and 2). CONCLUSION: The pregnancy rate by cycle and by transfer reported by ICSI (p < 0.003 and p < 0.015 respectively) could be related to a significantly higher mean number of transferred embryos (2.65 vs 2.02) in probable relation with a higher cleavage rate (p < 0.00001).

[Intraperitoneal insemination]. / Inséminations intrapéritonéales.

Intra-perineal insemination is a technique used in assisted reproduction. The principle is to stimulate the ovaries, to obtain the partner's sperm and to prepare it by similar techniques to those used in in-vitro fertilization so that the sperm can be placed near the ovaries in the Pouch of Douglas by a direct puncture of the posterior vaginal fornix without using anaesthesia. The woman's pelvis has to be absolutely normal. This technique is useful in cases of unexplained sterility, cervical sterility and inadequate sperm function.

[46 XX karyotype men (author's transl)]. / Les hommes à caryotype 46, XX.

85 cases of this syndrom have been published since the original case in 1964. The main clinical symptoms are those of Klinefelter's disease from which it differs by the caryotype only. Azoospermie is the rule. 3 mechanisms can be implicated: Mosaic 46 XX/47 XY with secondary loss of Y chromosome; Translocation of a part of Y chromosome upon an autosome or Y chromosome; Autosomal mutant gene acting upon the masculinizing site of X chromosome and inducing the primitive development of the testis as the short arm and proximal part of the long arm of Y chromosome normally do. These mechanisms perhaps are distinct origins of a syndrom which clinic alone cannot dissociate.

[Apparent internal male pseudo-hermaphroditism. Gynecomastia. Negative gonad surgical research. Caryotype 46, XX. Presence of H-Y antigen (author's transl)]. / Pseudo-hermaphrodisme mâle interne apparent. Gynécomastie. Recherche chirurgicale des gonades négatives. Caryotype 46, XX. Présence d'antigène H-Y.

Boy 15. Aspect of delayed puberty with empty scrotum and gynecomastia. Caryotype 46, XX. Presence of H.Y. Antigen. Plasmatic testosterone 1 020 pg/ml. Normal plasmatic FSH and LH. Hypotrophic uterus and tubes. No gonad found. Small right epididymis. Complete virilization by testosterone.

[Genetic aspects of male infertility]. / Aspects génétiques de la stérilité masculine.

Cytogenetic investigations in sterile males showed that autosomal and sex chromosome anomalies can be responsible of the defect of spermatogenesis. Specific alteration of genes controlling spermatogenesis is excluded because all chromosomes are involved in the anomaly and breakpoints are distributed at random. In the aim to explain the spermatogenic failure, three mechanisms are proposed: X-autosome interaction, asynapsis, somatic lesion of the gonad, each mechanism might act alone or with the other. Beside chromosomal infertility, meiotic or sperm anomalies suggest the presence of gene mutations which interfere with the evolution of spermatogenesis or lead to the formation of abnormal spermatozoa. Insertion of technics of molecular biology in our researches could demonstrate the existence of these mutations; the same technics will allow to resolve the problem of the failure of a germ cell bearing a chromosomal anomaly particularly when this anomaly is balanced and involves the autosomes and not the sex chromosomes.

[The gene content of the Y chromosome in men]. / Le contenu génétique du chromosome Y de l'homme.

The great variety of structural anomalies found in the Y chromosome makes it possible to assign particular roles to certain regions of it, gonadal differentiation to one place and testicular development and morphogenesis to others. The facts and hypotheses concerning the gene content of the Y chromosome are discussed.

[Incidence of structural chromosomal abnormalities in spermatogenesis in man]. / L'incidence des anomalies chromosomiques de structure sur la spermatogenèse chez l'homme.

Infertility due to gametogenic failure is frequently associated with structural autosomal abnormalities. Recent meiotic studies at the pachytene stage undertaken in human infertile heterozygous carriers for such rearrangements have regularly shown a synaptic failure around the breakpoints, an association of the translocation figure with the sex chromosomes and the frequent involvement of the acrocentric chromosomes. Two main models were proposed to explain the male sterilizing effect of autosomal rearrangements: the impairment of spermatogenesis could be the result of: 1) the XY-autosome interaction; 2) the pairing disruption around the breakpoints at the pachytene stage. They could contribute significantly to germ-cell atresia.

[Do male germ cells begin meiosis during fetal life?]. / Les cellules germinales males sont-elles aptes a entrer en meiose pendant la periode foetale?

The existence of a preleptotene chromosome condensation and decondensation stage occuring between the last premeiotic interphase and the leptotene stage was described in numberous plants. This stage was also reported in the human fetal oocyte and in various animals (rabbit, sheep, mouse). A similar process of chromosome condensation was described in the human foetal testis, but in this latter, the decondensation phase leading to leptotene was never observed. According to this observation and to various experimental results from the literature, the preleptotene condensation stage could be related to the processes of meiotic initiation. It could represent a phase of transition between mitotic and meiotic behaviour during which the germinal cell could be sensitive to meiosis-inducing factors. It is suggested that the male germinal cell 46,XY could enter meiosis. This hypothesis is confirmed by the observation of the capacity of the XY germ cell in the mouse to become an oocyte. This capacity is normally not expressed, due to the repressive control of the adjacent Sertoli cells. Thus, stimulation of the germinal cell to enter meiosis could result from environmental factors rather than from a genetic programmation.