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Observations on the So-Called Sex Chromatin in Man

Published online by Cambridge University Press:  01 August 2014

Juhan Reitalu*
Affiliation:
Cancer Chromosome Laboratory, Institute of Genetics, Lund, Sweden

Summary

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The difference in nuclear structure between male and female tissues in man has been examined in liver tissue from three embryos of each sex. The so-called sex chromatin consists of a large heterochromatic segment of the X chromosome, thus existing in duplicate in female diploid cells. The two segments have a tendency of juxtaposition resulting in a larger heterochromatic body in female than in male cells. Beside the large heterochromatic segment the X chromosome has, in the tissues studied, a euchromatic segment attached through a small terminal heterochromatic knob to a nucleolus. In male cells the euchromatic segment of the X chromosome is often joined terminally to a small heterochromatic segment believed to belong to the Y chromosome.

Sommario

SOMMARIO

La differenza di struttura nucleare fra i tessuti maschili e femminili nell'uomo è stata esaminata nel tessuto del fegato su tre embrioni di ciascun sesso. Ciò che si chiama la cromatinasessuale consiste in un grande segmento eterocromatico di cromosoma X, esistente però in doppio nelle cellule diploidi femminili. I due segmenti hanno una tendenza di giustapposizione formante un corpo eterocromatico più grande nelle cellule femminili che in quelle maschili. A parte del grande segmento eterocromatico il cromosoma X possiede, nei tessuti studiati, un segmento eucromatico attaccato ad un nucleolo da una piccola protuberanza eterocromatica terminale. Nelle cellule maschili il segmento eucromatico del cromosoma X è sovente attaccato, alla sua estremità, ad un piccolo segmento eterocromatico che si crede appartenga al cromosoma Y.

Sommaire

SOMMAIRE

La différence de structure nucléaire entre des tissus masculins et féminins chez l'homme a été examinée dans le tissu du foie sur trois embryons de chaque sexe. Ce qu'on appelle la chromatine sexuée consiste dans un grand segment hétérochromatique du chromosome X, existant ainsi en double dans des cellules diploïdes féminines. Les deux segments ont une tendance de justaposition formant un corps hétérochromatique plus grand dans des cellules féminines que dans les masculines. A côté du grand segment hétérochromatique le chromosome X possède dans les tissus étudiés un segment euchromatique attaché à un nucléolus par une petite protubérance hétérochromatique terminale. Dans les cellules masculines le segment euchromatique du chromosone X est souvent attaché à son extrémité à un petit segment hétérochromatique qu'on croit appartenir au chromosome Y.

Zusammenfassung

ZUSAMMENFASSUNG

Der Unterschied des Kernbaus zwischen männlichen und weiblichen Geweben im menschlichen Körper ist im Lebergewebe von drei Embryen jedes Geschlechtes untersucht worden. Die sogenannte Geschlechtschromatin besteht aus einem grossen heterachromatischen Segmente des X-Chromosoms, das also in weiblichen diploiden Zellen vorkommt. Die zwei Segmente haben eine Neigung zur Nebeneinanderstellung und bilden in weiblichen Zellen einen grösseren heterochromatischen Körper als in männlichen. Neben dem grossen heterochromatischen Segmente hat das X-Chromosom in den untersuchten Geweben ein euchromatisches Segment, das durch einen kleinen heterochromatischen Endhöcker mit einem Kernkörperchen verbunden ist. In männlichen Zellen ist das euchromatische Segment des X-Chromosoms oft am Ende mit einem kleinen heterochromatischen Segmente verbunden, von dem man glaubt, dass es zum Y-Chromosom gehört.

Type
Research Article
Copyright
Copyright © The International Society for Twin Studies 1957

References

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