Man & woman, boy & girl : the differentiation and dimorphism of gender identity from conception to maturity / by John Money and Anke A. Ehrhardt.

  • John Money
Date:
[1972]
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Man & woman, boy & girl : the differentiation and dimorphism of gender identity from conception to maturity / by John Money and Anke A. Ehrhardt. Source: Wellcome Collection.

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    29 GENETIC DIMORPHISM Human Cytogenetic Syndromes The occurrence of atypical genotypes in human beings is not the result of a planned experiment, as in animals, but of Nature's own caprice—one resorts to the concept of caprice, because there is not yet a systematic and coherent explanation of what, in the very basic sense, causes the phenomenon of abnormal genotypes. The mechanism of how a particular chromosomal anomaly occurs in the course of cell division and reproduc¬ tion, at the very beginning of life, has been spelled out in many texts (for example, Bartalos and Baramki [1967]), but the stimulus of its occurrence is not yet well understood. With respect to the X and the Y chromosome in human beings, the anomalies that have so far been discovered involve either the loss of one chromosome or the addition of one or more too many. Concerning chromo¬ somal loss, it is possible for one of the X chromosomes from the XX pair, or for the Y from the XY pair, to be lost without a lethal effect—the fer¬ tilized X cell divides and grows through embryonic life to produce always the body type of a female, though minus fertility. By contrast, the loss of an X chromosome from an XY combination, leaving only a Y (45,Y) is lethal. No human beings have been found with a 45,Y chromosomal pat¬ tern. In the case not of chromosome loss but addition, it is not lethal if either one or more than one of the X or Y chromosomes gets incorporated into the fertilized cell. Among the viable genetic possibilities so far dis¬ covered are XXX, XXY and XYY, and there are others also, including mosaicism, the condition in which some of the cells of a given individual have one or more supernumerary chromosomes, or a missing chromosome, while the others do not. One may infer with confidence from today's accumulated cytogenetic information that, in the absence of a single Y chromosome, the body type differentiates as female. When at least one Y chromosome is present, the body type will differentiate as male, unless some special genetic or intrauterine biochemical factor inter¬ venes to inhibit masculinity. It first became possible to spell out the relationship between a missing or extra X or Y chromosome and the sexual dimorphism of body type after Tjio and Levan (1956), working with a new technique for counting chromosomes, proved that the number of human chromosomes is 46 and not 48, as had until then been thought (Figure 2.3). They opened the way for the first time in history to the accurate counting of human chromo¬ somes as a routine, albeit still tedious and expensive, laboratory test. In 1959, the first reports came in of abnormal numbers of chromosomes in certain chnical cases, for example. Turner's (45,X) syndrome and Kline-