58 



BIOLOGIC BASIS OF SEX 



to a diploid female host where they may at- 

 tach to the oviducts and release eggs for 

 fertilization (Beadle and Ephrussi, 1937). 



These cases present confirmation of two 

 facts already mentioned for Drosophila. 

 They show that when the X chromosome 

 has primarily sex determining genes, the 

 organism generally becomes unbalanced 

 when 3 of these X chromosomes are matched 

 against two sets of autosomes. The re- 

 sulting phenotypes are female but relatively 

 undeveloped rather than overdeveloped. 

 The second is that the connotations evoked 

 by the prefix "super" are by no means ap- 

 plicable to this human type or to the Dro- 

 sophila type. 



The characteristics of the patient also 

 suggest that the autosomes may be carrying 

 sex genes opposing those of female tenden- 

 cies as observed in both Drosophila and 

 Rumex genie imbalance. 



5. Klinefelter Syndrome 



In the Klinefelter syndrome there is male 

 differentiation of the reproductive tracts 

 with small firm descended testes. Meiotic or 

 mitotic divisions are rare, sperm are ordi- 

 narily not found in the semen. The type is 

 eunuchoid in appearance with gyneco- 

 mastia, high-pitched voice, and sparse fa- 

 cial hair growth. Seminiferous tubules show- 

 ing an increased number of interstitial cells 

 are atrophic and hyalinized. Urinary excre- 

 tion of pituitary gonadotrophins is generally 

 increased, whereas the level of 17-keto- 

 steroids may be decreased. The nuclear 

 chromatin is typically female. Of the dozen 

 or more cases studied (Jacobs and Strong, 

 1959; Ford, Jones, Miller, Mittwoch, Pen- 

 rose, Ridler and Sha])iro, 1959; Bergman 

 and Reitalu quoted by Ford, 1960), only 

 one, having but 5 metaphase figures, had 

 less than 47 chromosomes in the somatic 

 cells and XXY sex chromosomes. That case 

 was thought to have typical female chro- 

 mosomes XX + 22 AA. Two other cases were 

 of particular interest as indicating further 

 chromosome aberration. Ford, Jones, Miller, 

 Mittwoch, Penrose, Ridler and Shapiro 

 (1959) studied one patient who displayed 

 both the Klinefelter and Mongoloid syn- 

 dromes. The chromosome number was 48, 

 the sex chromosomes being XXY and the 

 48tli chromosoinc being small acrocentric. 



This individual had evidently developed 

 from an egg carrying 2 chromosomal aberra- 

 tions, one for the sex chromosomes and the 

 second for one of the autosomes. The other 

 case, Bergman and Reitalu as cited by 

 Ford (1960), had 30 per cent of its cells 

 with an additional acrocentric chromosome 

 which had no close counterpart in the nor- 

 mal set. 



Data where the Klinefelter syndrome oc- 

 curs in families showing color blindness 

 (Polani, Bishop, Ferguson-Smith, Lennox, 

 Stewart and Prader, 1958; Nowakowski, 

 Lenz and Parada, 1959; and Stern, 1959a) 

 further test the XXY relationship and give 

 information on the possible position of the 

 color blindness locus with reference to the 

 kinetochore. Polani, Bishop, Ferguson- 

 Smith, Lennox, Stewart and Prader (1958) 

 tested 72 sex chromatin-positive Klinefelter 

 patients for their color vision and found 

 that none was affected by red-green color 

 blindness. Nowakowski, Lenz and Parada 

 ( 1959) tested 34 cases and detected 3 af- 

 fected persons, 2 of whom were deutera- 

 nomalous and one protanopic. Stern (1959a) 

 l^oints out that these cases and their ratios 

 are compatible with the interpretation of 

 the Klinefelter syndrome as XXY. One of 

 the deuteranomalous cases had a deutera- 

 nomalous mother and a father with normal 

 color vision. This case could have originated 

 from a nondisjunctional egg carrying 2 

 maternal X chromosomes fertilized by a 

 sperm carrying a Y chromosome. The other 

 two cases had normal fathers with hetero- 

 zygous mothers. There are several explana- 

 tions by which the color-blind Klinefelter 

 progenies could be obtained. The hetero- 

 zygotes might manifest the color-blind con- 

 dition. The second hypothesis, which is 

 favored, is that of crossing over between the 

 kinetochore and the color-blind locus at the 

 first meiotic division to form eggs each 

 carrying 2 X chromosomes, one homozygous 

 for color blindness, and the other for normal 

 vision. An equational nondisjunction would 

 form eggs homozygous for color blindness 

 which on fertilization by the Y chromo- 

 somes of the male would give the necessary 

 XXY constitution for the color-blind male 

 which is Klinefelter in phenotype. A third 

 possibiHty is that these exceptions may 

 arise without crossing over as the result of 



