title: [Oocyte meiosis in a trisomy 18 fetus. Behavior of the supernumerary chromosome and identification of the 18 bivalent].
abstract: Associations of the three n degrees 18 chromosomes were studied in a trisomy 18 fetus (the chromosomal constitution of which had been identified by amniocentesis). The three classes of associations observed were those observed in other trisomic organisms:trivalent, trivalent presenting an important asynaptic region, and bivalent accompanied by a univalent. In addition, the sequence was established of chromomeres, the number of which varied from 18 to 23 depending on the degree of chromosome contraction. In elongated pachytene oocyte bivalents each G-band of mitotic metaphase chromosomes could be subdivided into several sub-bands.
mesh_terms: D002871:Chromosome Banding; D002902:Chromosomes, Human, 16-18; D005260:Female; D005333:Fetus / Q000473:pathology; D006801:Humans; D007621:Karyotyping; D008540:Meiosis; D009865:Oocytes / Q000166:cytology*; D010063:Ovum / Q000166:cytology*; D014314:Trisomy
vernacular_title: Etude de la méiose ovocytaire chez un foetus trisomique 18. Comportement du chromosome surnuméraire et identification du bivalent 18.